diff --git a/addons/crm/__manifest__.py b/addons/crm/__manifest__.py
index 75b071d3ee4..8518fa6630f 100644
--- a/addons/crm/__manifest__.py
+++ b/addons/crm/__manifest__.py
@@ -4,7 +4,7 @@
 
 {
     'name': 'CRM',
-    'version': '1.5',
+    'version': '1.6',
     'category': 'Sales/CRM',
     'sequence': 15,
     'summary': 'Track leads and close opportunities',
diff --git a/addons/crm/models/crm_lead.py b/addons/crm/models/crm_lead.py
index 42a51605f3b..ba6ff745235 100644
--- a/addons/crm/models/crm_lead.py
+++ b/addons/crm/models/crm_lead.py
@@ -225,7 +225,8 @@ class Lead(models.Model):
         'crm.lost.reason', string='Lost Reason',
         index=True, ondelete='restrict', tracking=True)
     # Statistics
-    meeting_count = fields.Integer('# Meetings', compute='_compute_meeting_count')
+    calendar_event_ids = fields.One2many('calendar.event', 'opportunity_id', string='Meetings')
+    calendar_event_count = fields.Integer('# Meetings', compute='_compute_calendar_event_count')
     duplicate_lead_ids = fields.Many2many("crm.lead", compute="_compute_potential_lead_duplicates", string="Potential Duplicate Lead", context={"active_test": False})
     duplicate_lead_count = fields.Integer(compute="_compute_potential_lead_duplicates", string="Potential Duplicate Lead Count")
     # UX
@@ -504,7 +505,7 @@ class Lead(models.Model):
         for lead in self:
             lead.recurring_revenue_monthly_prorated = (lead.recurring_revenue_monthly or 0.0) * (lead.probability or 0) / 100.0
 
-    def _compute_meeting_count(self):
+    def _compute_calendar_event_count(self):
         if self.ids:
             meeting_data = self.env['calendar.event'].sudo().read_group([
                 ('opportunity_id', 'in', self.ids)
@@ -513,7 +514,7 @@ class Lead(models.Model):
         else:
             mapped_data = dict()
         for lead in self:
-            lead.meeting_count = mapped_data.get(lead.id, 0)
+            lead.calendar_event_count = mapped_data.get(lead.id, 0)
 
     @api.depends('email_from', 'partner_id', 'contact_name', 'partner_name')
     def _compute_potential_lead_duplicates(self):
@@ -1310,62 +1311,6 @@ class Lead(models.Model):
         message_body = "\n\n".join(message_bodies)
         return self.message_post(body=message_body, subject=subject)
 
-    def _merge_opportunity_history(self, opportunities):
-        """ Move mail.message from the given opportunities to the current one. `self` is the
-            crm.lead record destination for message of `opportunities`.
-
-        :param opportunities: see ``_merge_dependences``
-        """
-        self.ensure_one()
-        for opportunity in opportunities:
-            for message in opportunity.message_ids:
-                if message.subject:
-                    subject = _("From %(source_name)s : %(source_subject)s", source_name=opportunity.name, source_subject=message.subject)
-                else:
-                    subject = _("From %(source_name)s", source_name=opportunity.name)
-                message.write({
-                    'res_id': self.id,
-                    'subject': subject,
-                })
-        return True
-
-    def _merge_opportunity_attachments(self, opportunities):
-        """ Move attachments of given opportunities to the current one `self`, and rename
-            the attachments having same name than native ones.
-
-        :param opportunities: see ``_merge_dependences``
-        """
-        self.ensure_one()
-
-        # return attachments of opportunity
-        def _get_attachments(opportunity_id):
-            return self.env['ir.attachment'].search([('res_model', '=', self._name), ('res_id', '=', opportunity_id)])
-
-        first_attachments = _get_attachments(self.id)
-        # counter of all attachments to move. Used to make sure the name is different for all attachments
-        count = 1
-        for opportunity in opportunities:
-            attachments = _get_attachments(opportunity.id)
-            for attachment in attachments:
-                values = {'res_id': self.id}
-                for attachment_in_first in first_attachments:
-                    if attachment.name == attachment_in_first.name:
-                        values['name'] = "%s (%s)" % (attachment.name, count)
-                count += 1
-                attachment.write(values)
-        return True
-
-    def _merge_dependences(self, opportunities):
-        """ Merge dependences (messages, attachments, ...). These dependences will be
-            transfered to `self`, the most important lead.
-
-        :param opportunities : recordset of opportunities to transfer. Does not
-          include `self` which is the target crm.lead being the result of the merge.
-        """
-        self.ensure_one()
-        self._merge_opportunity_history(opportunities)
-        self._merge_opportunity_attachments(opportunities)
-
     def merge_opportunity(self, user_id=False, team_id=False, auto_unlink=True):
         """ Merge opportunities in one. Different cases of merge:
                 - merge leads together = 1 new lead
@@ -1439,6 +1384,88 @@ class Lead(models.Model):
     def _merge_get_fields(self):
         return list(CRM_LEAD_FIELDS_TO_MERGE) + list(self._merge_get_fields_specific().keys())
 
+    def _merge_dependences(self, opportunities):
+        """ Merge dependences (messages, attachments,activities, calendar events,
+        ...). These dependences will be transfered to `self` considered as the
+        master lead.
+
+        :param opportunities : recordset of opportunities to transfer. Does not
+          include `self` which is the target crm.lead being the result of the
+          merge;
+        """
+        self.ensure_one()
+        self._merge_dependences_history(opportunities)
+        self._merge_dependences_attachments(opportunities)
+        self._merge_dependences_calendar_events(opportunities)
+
+    def _merge_dependences_history(self, opportunities):
+        """ Move history from the given opportunities to the current one. `self`
+        is the crm.lead record destination for message of `opportunities`.
+
+        This method moves
+          * messages
+          * activities
+
+        :param opportunities: see ``_merge_dependences``
+        """
+        self.ensure_one()
+        for opportunity in opportunities:
+            for message in opportunity.message_ids:
+                if message.subject:
+                    subject = _("From %(source_name)s : %(source_subject)s", source_name=opportunity.name, source_subject=message.subject)
+                else:
+                    subject = _("From %(source_name)s", source_name=opportunity.name)
+                message.write({
+                    'res_id': self.id,
+                    'subject': subject,
+                })
+
+        opportunities.activity_ids.write({
+            'res_id': self.id,
+        })
+
+        return True
+
+    def _merge_dependences_attachments(self, opportunities):
+        """ Move attachments of given opportunities to the current one `self`, and rename
+            the attachments having same name than native ones.
+
+        :param opportunities: see ``_merge_dependences``
+        """
+        self.ensure_one()
+
+        all_attachments = self.env['ir.attachment'].search([
+            ('res_model', '=', self._name),
+            ('res_id', 'in', opportunities.ids)
+        ])
+
+        for opportunity in opportunities:
+            attachments = all_attachments.filtered(lambda attach: attach.res_id == opportunity.id)
+            for attachment in attachments:
+                attachment.write({
+                    'res_id': self.id,
+                    'name': _("%(attach_name)s (from %(lead_name)s)",
+                              attach_name=attachment.name,
+                              lead_name=opportunity.name[:20]
+                             )
+                })
+        return True
+
+    def _merge_dependences_calendar_events(self, opportunities):
+        """ Move calender.event from the given opportunities to the current one. `self` is the
+            crm.lead record destination for event of `opportunities`.
+        :param opportunities: see ``merge_dependences``
+        """
+        self.ensure_one()
+        meetings = self.env['calendar.event'].search([('opportunity_id', 'in', opportunities.ids)])
+        return meetings.write({
+            'res_id': self.id,
+            'opportunity_id': self.id,
+        })
+
+    # CONVERT
+    # ----------------------------------------------------------------------
+
     def _convert_opportunity_data(self, customer, team_id=False):
         """ Extract the data from a lead to create the opportunity
             :param customer : res.partner record
diff --git a/addons/crm/tests/common.py b/addons/crm/tests/common.py
index 2147169e8cc..f863b577c94 100644
--- a/addons/crm/tests/common.py
+++ b/addons/crm/tests/common.py
@@ -53,6 +53,7 @@ class TestCrmCommon(TestSalesCommon, MailCase):
         'phone', 'probability', 'expected_revenue', 'street', 'street2', 'zip',
         'create_date', 'date_action_last', 'email_from', 'email_cc', 'website'
     ]
+    merge_fields = ['description', 'type', 'priority']
 
     @classmethod
     def setUpClass(cls):
@@ -210,6 +211,21 @@ class TestCrmCommon(TestSalesCommon, MailCase):
             'zip': '87654',
         })
 
+        # test activities
+        cls.activity_type_1 = cls.env['mail.activity.type'].create({
+            'name': 'Lead Test Activity 1',
+            'summary': 'ACT 1 : Presentation, barbecue, ... ',
+            'res_model_id': cls.env['ir.model']._get('crm.crm_lead').id,
+            'category': 'meeting',
+            'delay_count': 5,
+        })
+        cls.env['ir.model.data'].create({
+            'name': cls.activity_type_1.name.lower().replace(' ', '_'),
+            'module': 'crm',
+            'model': cls.activity_type_1._name,
+            'res_id': cls.activity_type_1.id,
+        })
+
     def _create_leads_batch(self, lead_type='lead', count=10, email_dup_count=0,
                             partner_count=0, partner_ids=None, user_ids=None,
                             country_ids=None, probabilities=None):
@@ -361,12 +377,11 @@ class TestCrmCommon(TestSalesCommon, MailCase):
         self.assertIn(opportunity, leads)
 
         # save opportunity value before being modified by merge process
-        fields_all = self.FIELDS_FIRST_SET + ['description', 'type', 'priority']
-        # ensure tests are synchronized with crm code
-        self.assertTrue(all(field in fields_all for field in CRM_LEAD_FIELDS_TO_MERGE + list(self.env['crm.lead']._merge_get_fields_specific().keys())))
+        fields_all = self.FIELDS_FIRST_SET + self.merge_fields
         original_opp_values = dict(
             (fname, opportunity[fname])
             for fname in fields_all
+            if fname in opportunity
         )
 
         def _find_value(lead, fname):
@@ -390,6 +405,13 @@ class TestCrmCommon(TestSalesCommon, MailCase):
             values = [_find_value(lead, 'priority') for lead in leads]
             return max(values)
 
+        def _aggregate(fname):
+            if isinstance(self.env['crm.lead'][fname], models.BaseModel):
+                values = leads.mapped(fname)
+            else:
+                values = [_find_value(lead, fname) for lead in leads]
+            return values
+
         try:
             # merge process will modify opportunity
             yield
@@ -400,6 +422,8 @@ class TestCrmCommon(TestSalesCommon, MailCase):
 
             # classic fields: first not void wins or specific computation
             for fname in fields_all:
+                if fname not in opportunity:  # not all fields available when doing -u
+                    continue
                 opp_value = opportunity[fname]
                 if fname == 'description':
                     self.assertEqual(opp_value, _get_description())
@@ -407,6 +431,8 @@ class TestCrmCommon(TestSalesCommon, MailCase):
                     self.assertEqual(opp_value, _get_type())
                 elif fname == 'priority':
                     self.assertEqual(opp_value, _get_priority())
+                elif fname in ('order_ids', 'visitor_ids'):
+                    self.assertEqual(opp_value, _aggregate(fname))
                 else:
                     self.assertEqual(
                         opp_value if opp_value or not isinstance(opp_value, models.BaseModel) else False,
diff --git a/addons/crm/tests/test_crm_lead_merge.py b/addons/crm/tests/test_crm_lead_merge.py
index de4aa826b37..97206dfec73 100644
--- a/addons/crm/tests/test_crm_lead_merge.py
+++ b/addons/crm/tests/test_crm_lead_merge.py
@@ -1,19 +1,21 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
+import base64
+
 from odoo.addons.crm.tests.common import TestLeadConvertMassCommon
 from odoo.fields import Datetime
 from odoo.tests.common import tagged, users
 
 
 @tagged('lead_manage')
-class TestLeadMerge(TestLeadConvertMassCommon):
+class TestLeadMergeCommon(TestLeadConvertMassCommon):
     """ During a mixed merge (involving leads and opps), data should be handled a certain way following their type
     (m2o, m2m, text, ...). """
 
     @classmethod
     def setUpClass(cls):
-        super(TestLeadMerge, cls).setUpClass()
+        super(TestLeadMergeCommon, cls).setUpClass()
 
         cls.leads = cls.lead_1 + cls.lead_w_partner + cls.lead_w_contact + cls.lead_w_email + cls.lead_w_partner_company + cls.lead_w_email_lost
         # reset some assigned users to test salesmen assign
@@ -29,6 +31,10 @@ class TestLeadMerge(TestLeadConvertMassCommon):
 
         cls.assign_users = cls.user_sales_manager + cls.user_sales_leads_convert + cls.user_sales_salesman
 
+
+@tagged('lead_manage')
+class TestLeadMerge(TestLeadMergeCommon):
+
     def test_initial_data(self):
         """ Ensure initial data to avoid spaghetti test update afterwards """
         self.assertFalse(self.lead_1.date_conversion)
@@ -160,3 +166,58 @@ class TestLeadMerge(TestLeadConvertMassCommon):
                                    partner_id=self.contact_company_1,
                                    priority='2'):
             leads._merge_opportunity(auto_unlink=False, max_length=None)
+
+    @users('user_sales_manager')
+    def test_merge_method_dependencies(self):
+        """ Test if dependences for leads are not lost while merging leads. In
+        this test leads are ordered as
+
+        lead_w_partner_company ---opp----seq=1 (ID greater)
+        lead_w_contact -----------lead---seq=30
+        lead_w_email -------------lead---seq=3----------------attachments
+        lead_1 -------------------lead---seq=1----------------activity+meeting
+        lead_w_partner -----------lead---seq=False
+        """
+        self.env['crm.lead'].browse(self.lead_w_partner_company.ids).write({'type': 'opportunity'})
+
+        # create side documents
+        attachments = self.env['ir.attachment'].create([
+            {'name': '%02d.txt' % idx,
+             'datas': base64.b64encode(b'Att%02d' % idx),
+             'res_model': 'crm.lead',
+             'res_id': self.lead_w_email.id,
+            } for idx in range(4)
+        ])
+        lead_1 = self.env['crm.lead'].browse(self.lead_1.ids)
+        activity = lead_1.activity_schedule('crm.lead_test_activity_1')
+        calendar_event = self.env['calendar.event'].create({
+            'name': 'Meeting with partner',
+            'activity_ids': [(4, activity.id)],
+            'start': '2021-06-12 21:00:00',
+            'stop': '2021-06-13 00:00:00',
+            'res_model_id': self.env['ir.model']._get('crm.crm_lead').id,
+            'res_id': lead_1.id,
+            'opportunity_id': lead_1.id,
+        })
+
+        # run merge and check documents are moved to the master record
+        merge = self.env['crm.merge.opportunity'].with_context({
+            'active_model': 'crm.lead',
+            'active_ids': self.leads.ids,
+            'active_id': False,
+        }).create({
+            'team_id': self.sales_team_convert.id,
+            'user_id': False,
+        })
+        result = merge.action_merge()
+        master_lead = self.leads.filtered(lambda lead: lead.id == result['res_id'])
+
+        # check result of merge process
+        self.assertEqual(master_lead, self.lead_w_partner_company)
+        # records updated
+        self.assertEqual(calendar_event.opportunity_id, master_lead)
+        self.assertEqual(calendar_event.res_id, master_lead.id)
+        self.assertTrue(all(att.res_id == master_lead.id for att in attachments))
+        # 2many accessors updated
+        self.assertEqual(master_lead.activity_ids, activity)
+        self.assertEqual(master_lead.calendar_event_ids, calendar_event)
diff --git a/addons/crm/views/crm_lead_views.xml b/addons/crm/views/crm_lead_views.xml
index 6e874e178cf..4a7c45ad514 100644
--- a/addons/crm/views/crm_lead_views.xml
+++ b/addons/crm/views/crm_lead_views.xml
@@ -30,9 +30,9 @@
                                 context="{'partner_id': partner_id}"
                                 attrs="{'invisible': [('type', '=', 'lead')]}">
                                 <div class="o_stat_info">
-                                    <field name="meeting_count" class="o_stat_value"/>
-                                    <span class="o_stat_text" attrs="{'invisible': [('meeting_count', '&lt;', 2)]}"> Meetings</span>
-                                    <span class="o_stat_text" attrs="{'invisible': [('meeting_count', '&gt;', 1)]}"> Meeting</span>
+                                    <field name="calendar_event_count" class="o_stat_value"/>
+                                    <span class="o_stat_text" attrs="{'invisible': [('calendar_event_count', '&lt;', 2)]}"> Meetings</span>
+                                    <span class="o_stat_text" attrs="{'invisible': [('calendar_event_count', '&gt;', 1)]}"> Meeting</span>
                                 </div>
                             </button>
                             <button name="action_show_potential_duplicates" type="object"
diff --git a/addons/crm/views/res_partner_views.xml b/addons/crm/views/res_partner_views.xml
index 10947a6eb59..c8b8d383393 100644
--- a/addons/crm/views/res_partner_views.xml
+++ b/addons/crm/views/res_partner_views.xml
@@ -11,7 +11,6 @@
             <field name="arch" type="xml">
                 <field name="mobile" position="after">
                     <field name="opportunity_count"/>
-                    <field name="meeting_count"/>
                 </field>
                 <xpath expr="//span[hasclass('oe_kanban_partner_links')]" position="inside">
                     <span class="badge badge-pill" t-if="record.opportunity_count.value>0"><i class="fa fa-fw fa-star" aria-label="Favorites" role="img" title="Favorites"/><t t-esc="record.opportunity_count.value"/></span>
diff --git a/addons/event_crm/models/crm_lead.py b/addons/event_crm/models/crm_lead.py
index 751cb58f333..de709404e95 100644
--- a/addons/event_crm/models/crm_lead.py
+++ b/addons/event_crm/models/crm_lead.py
@@ -22,3 +22,11 @@ class Lead(models.Model):
     def _compute_registration_count(self):
         for record in self:
             record.registration_count = len(record.registration_ids)
+
+    def _merge_dependences(self, opportunities):
+        super(Lead, self)._merge_dependences(opportunities)
+
+        # merge registrations as sudo, as crm people may not have access to event rights
+        self.sudo().write({
+            'registration_ids': [(4, registration.id) for registration in opportunities.sudo().registration_ids]
+        })
diff --git a/addons/event_crm/tests/__init__.py b/addons/event_crm/tests/__init__.py
index 4d35e728d96..168e85398aa 100644
--- a/addons/event_crm/tests/__init__.py
+++ b/addons/event_crm/tests/__init__.py
@@ -2,3 +2,4 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 from . import test_event_crm_flow
+from . import test_crm_lead_merge
diff --git a/addons/event_crm/tests/test_crm_lead_merge.py b/addons/event_crm/tests/test_crm_lead_merge.py
new file mode 100644
index 00000000000..55cf7638cbc
--- /dev/null
+++ b/addons/event_crm/tests/test_crm_lead_merge.py
@@ -0,0 +1,37 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo.addons.crm.tests.test_crm_lead_merge import TestLeadMergeCommon
+from odoo.addons.event_crm.tests.common import TestEventCrmCommon
+from odoo.tests.common import tagged, users
+
+
+@tagged('lead_manage')
+class TestLeadCrmMerge(TestLeadMergeCommon, TestEventCrmCommon):
+
+    @users('user_sales_manager')
+    def test_merge_method_dependencies(self):
+        """ Test if dependences for leads are not lost while merging leads. In
+        this test leads are ordered as
+
+        lead_w_contact -----------lead---seq=30
+        lead_w_email -------------lead---seq=3
+        lead_1 -------------------lead---seq=1
+        lead_w_partner_company ---lead---seq=1----------------registrations
+        lead_w_partner -----------lead---seq=False
+        """
+        TestLeadMergeCommon.merge_fields.append('registration_ids')
+
+        registration = self.env['event.registration'].sudo().create({
+            'partner_id': self.event_customer.id,
+            'event_id': self.event_0.id,
+            'lead_ids': [(4, self.lead_w_partner_company.id)],
+        })
+        self.assertEqual(self.lead_w_partner_company.registration_ids, registration)
+
+        leads = self.env['crm.lead'].browse(self.leads.ids)._sort_by_confidence_level(reverse=True)
+        with self.assertLeadMerged(self.lead_w_contact, leads,
+                                   name=self.lead_w_contact.name,
+                                   registration_ids=registration
+                                   ):
+            leads._merge_opportunity(auto_unlink=False, max_length=None)
diff --git a/addons/sale_crm/models/crm_lead.py b/addons/sale_crm/models/crm_lead.py
index 59439949a01..f6311c8b4ff 100644
--- a/addons/sale_crm/models/crm_lead.py
+++ b/addons/sale_crm/models/crm_lead.py
@@ -83,3 +83,9 @@ class CrmLead(models.Model):
             action['views'] = [(self.env.ref('sale.view_order_form').id, 'form')]
             action['res_id'] = orders.id
         return action
+
+    def _merge_get_fields_specific(self):
+        fields_info = super(CrmLead, self)._merge_get_fields_specific()
+        # add all the orders from all lead to merge
+        fields_info['order_ids'] = lambda fname, leads: [(4, order.id) for order in leads.order_ids]
+        return fields_info
diff --git a/addons/sale_crm/tests/__init__.py b/addons/sale_crm/tests/__init__.py
index da4d8ac13b2..71291d19b32 100644
--- a/addons/sale_crm/tests/__init__.py
+++ b/addons/sale_crm/tests/__init__.py
@@ -2,3 +2,4 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 from . import test_crm_lead_convert_quotation
+from . import test_crm_lead_merge
diff --git a/addons/sale_crm/tests/test_crm_lead_merge.py b/addons/sale_crm/tests/test_crm_lead_merge.py
new file mode 100644
index 00000000000..ef525194eb7
--- /dev/null
+++ b/addons/sale_crm/tests/test_crm_lead_merge.py
@@ -0,0 +1,40 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo.addons.crm.tests.test_crm_lead_merge import TestLeadMergeCommon
+from odoo.tests.common import tagged, users
+
+
+@tagged('lead_manage')
+class TestLeadSaleMerge(TestLeadMergeCommon):
+
+    @users('user_sales_manager')
+    def test_merge_method_dependencies(self):
+        """ Test if dependences for leads are not lost while merging leads. In
+        this test leads are ordered as
+
+        lead_w_contact -----------lead---seq=30
+        lead_w_email -------------lead---seq=3
+        lead_1 -------------------lead---seq=1
+        lead_w_partner_company ---lead---seq=1----------------orders
+        lead_w_partner -----------lead---seq=False------------orders
+        """
+        TestLeadMergeCommon.merge_fields.append('order_ids')
+
+        orders = self.env['sale.order'].sudo().create([
+            {'partner_id': self.contact_1.id,
+             'opportunity_id': self.lead_w_partner_company.id,
+            },
+            {'partner_id': self.contact_1.id,
+             'opportunity_id': self.lead_w_partner.id,
+            }
+        ])
+        self.assertEqual(self.lead_w_partner_company.order_ids, orders[0])
+        self.assertEqual(self.lead_w_partner.order_ids, orders[1])
+
+        leads = self.env['crm.lead'].browse(self.leads.ids)._sort_by_confidence_level(reverse=True)
+        with self.assertLeadMerged(self.lead_w_contact, leads,
+                                   name=self.lead_w_contact.name,
+                                   order_ids=orders
+                                   ):
+            leads._merge_opportunity(auto_unlink=False, max_length=None)
diff --git a/addons/website_crm/tests/__init__.py b/addons/website_crm/tests/__init__.py
index ba4af1674ec..74be5959a41 100644
--- a/addons/website_crm/tests/__init__.py
+++ b/addons/website_crm/tests/__init__.py
@@ -3,3 +3,4 @@
 
 from . import test_website_crm
 from . import test_website_visitor
+from . import test_crm_lead_merge
diff --git a/addons/website_crm/tests/test_crm_lead_merge.py b/addons/website_crm/tests/test_crm_lead_merge.py
new file mode 100644
index 00000000000..a066266aeb2
--- /dev/null
+++ b/addons/website_crm/tests/test_crm_lead_merge.py
@@ -0,0 +1,40 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo.addons.crm.tests.test_crm_lead_merge import TestLeadMergeCommon
+from odoo.tests.common import tagged, users
+
+
+@tagged('lead_manage')
+class TestLeadVisitorMerge(TestLeadMergeCommon):
+
+    @users('user_sales_manager')
+    def test_merge_method_dependencies(self):
+        """ Test if dependences for leads are not lost while merging leads. In
+        this test leads are ordered as
+
+        lead_w_contact -----------lead---seq=30
+        lead_w_email -------------lead---seq=3
+        lead_1 -------------------lead---seq=1
+        lead_w_partner_company ---lead---seq=1----------------visitor
+        lead_w_partner -----------lead---seq=False------------visitor
+        """
+        TestLeadMergeCommon.merge_fields.append('visitor_ids')
+
+        visitors = self.env['website.visitor'].sudo().create([
+            {'name': 'Visitor 1',
+             'lead_ids': [(4, self.lead_w_partner_company.id)],
+            },
+            {'name': 'Visitor 2',
+             'lead_ids': [(4, self.lead_w_partner.id)],
+            }
+        ])
+        self.assertEqual(self.lead_w_partner_company.visitor_ids, visitors[0])
+        self.assertEqual(self.lead_w_partner.visitor_ids, visitors[1])
+
+        leads = self.env['crm.lead'].browse(self.leads.ids)._sort_by_confidence_level(reverse=True)
+        with self.assertLeadMerged(self.lead_w_contact, leads,
+                                   name=self.lead_w_contact.name,
+                                   visitor_ids=visitors
+                                   ):
+            leads._merge_opportunity(auto_unlink=False, max_length=None)