diff --git a/addons/event_sale/models/sale_order.py b/addons/event_sale/models/sale_order.py
index 9f94ca70e19..fd589e41e8a 100644
--- a/addons/event_sale/models/sale_order.py
+++ b/addons/event_sale/models/sale_order.py
@@ -47,6 +47,10 @@ class SaleOrder(models.Model):
         for sale_order in self:
             sale_order.attendee_count = attendee_count_data.get(sale_order.id, 0)
 
+    def unlink(self):
+        self.order_line._unlink_associated_registrations()
+        return super(SaleOrder, self).unlink()
+
 
 class SaleOrderLine(models.Model):
 
@@ -120,6 +124,13 @@ class SaleOrderLine(models.Model):
         # we call this to force update the default name
         self.product_id_change()
 
+    def unlink(self):
+        self._unlink_associated_registrations()
+        return super(SaleOrderLine, self).unlink()
+
+    def _unlink_associated_registrations(self):
+        self.env['event.registration'].search([('sale_order_line_id', 'in', self.ids)]).unlink()
+
     def get_sale_order_line_multiline_description_sale(self, product):
         """ We override this method because we decided that:
                 The default description of a sales order line containing a ticket must be different than the default description when no ticket is present.
diff --git a/addons/event_sale/tests/test_event_sale.py b/addons/event_sale/tests/test_event_sale.py
index 8b8ab6c7d92..65a777ef6b0 100644
--- a/addons/event_sale/tests/test_event_sale.py
+++ b/addons/event_sale/tests/test_event_sale.py
@@ -2,6 +2,8 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 from odoo.addons.event_sale.tests.common import TestEventSaleCommon
+from odoo.addons.mail.tests.common import mail_new_test_user
+
 from odoo.tests import tagged
 from odoo.tests.common import users
 
@@ -13,20 +15,59 @@ class TestEventSale(TestEventSaleCommon):
     def setUpClass(cls):
         super(TestEventSale, cls).setUpClass()
 
+        product = cls.env['product.product'].create({
+            'name': 'Event',
+            'type': 'service',
+            'event_ok': True,
+        })
+
+        cls.user_salesperson = mail_new_test_user(cls.env, login='user_salesman', groups='sales_team.group_sale_salesman')
+
+        cls.ticket = cls.env['event.event.ticket'].create({
+            'name': 'First Ticket',
+            'product_id': cls.event_product.id,
+            'seats_max': 30,
+            'event_id': cls.event_0.id,
+        })
+
         cls.event_0.write({
             'event_ticket_ids': [
-                (5, 0),
+                (6, 0, cls.ticket.ids),
                 (0, 0, {
-                    'name': 'First Ticket',
-                    'product_id': cls.event_product.id,
-                    'seats_max': 30,
-                }), (0, 0, {
                     'name': 'Second Ticket',
                     'product_id': cls.event_product.id,
                 })
             ],
         })
 
+        cls.sale_order = cls.env['sale.order'].create({
+            'partner_id': cls.env.ref('base.res_partner_2').id,
+            'note': 'Invoice after delivery',
+            'payment_term_id': cls.env.ref('account.account_payment_term_end_following_month').id
+        })
+
+        # In the sales order I add some sales order lines. i choose event product
+        cls.env['sale.order.line'].create({
+            'product_id': product.id,
+            'price_unit': 190.50,
+            'product_uom': cls.env.ref('uom.product_uom_unit').id,
+            'product_uom_qty': 1.0,
+            'order_id': cls.sale_order.id,
+            'name': 'sales order line',
+            'event_id': cls.event_0.id,
+            'event_ticket_id': cls.ticket.id,
+        })
+
+        cls.register_person = cls.env['registration.editor'].create({
+            'sale_order_id': cls.sale_order.id,
+            'event_registration_ids': [(0, 0, {
+                'event_id': cls.event_0.id,
+                'name': 'Administrator',
+                'email': 'abc@example.com',
+                'sale_order_line_id': cls.sale_order.order_line.id,
+            })],
+        })
+
         # make a SO for a customer, selling some tickets
         cls.customer_so = cls.env['sale.order'].with_user(cls.user_sales_salesman).create({
             'partner_id': cls.event_customer.id,
@@ -209,3 +250,23 @@ class TestEventSale(TestEventSaleCommon):
         })
         sol.product_id_change()
         self.assertEqual(so.amount_total, 660.0, "Ticket is $1000 but the event product is on a pricelist 10 -> 6. So, $600 + a 10% tax.")
+
+    @users('user_salesman')
+    def test_unlink_so(self):
+        """ This test ensures that when deleting a sale order, if the latter is linked to an event registration,
+        the number of expected seats will be correctly updated """
+        event = self.env['event.event'].browse(self.event_0.ids)
+        self.register_person.action_make_registration()
+        self.assertEqual(event.seats_expected, 1)
+        self.sale_order.unlink()
+        self.assertEqual(event.seats_expected, 0)
+
+    @users('user_salesman')
+    def test_unlink_soline(self):
+        """ This test ensures that when deleting a sale order line, if the latter is linked to an event registration,
+        the number of expected seats will be correctly updated """
+        event = self.env['event.event'].browse(self.event_0.ids)
+        self.register_person.action_make_registration()
+        self.assertEqual(event.seats_expected, 1)
+        self.sale_order.order_line.unlink()
+        self.assertEqual(event.seats_expected, 0)
diff --git a/addons/event_sale/wizard/event_edit_registration.py b/addons/event_sale/wizard/event_edit_registration.py
index 9db556ba804..575bb1af4bd 100644
--- a/addons/event_sale/wizard/event_edit_registration.py
+++ b/addons/event_sale/wizard/event_edit_registration.py
@@ -7,7 +7,7 @@ class RegistrationEditor(models.TransientModel):
     _name = "registration.editor"
     _description = 'Edit Attendee Details on Sales Confirmation'
 
-    sale_order_id = fields.Many2one('sale.order', 'Sales Order', required=True)
+    sale_order_id = fields.Many2one('sale.order', 'Sales Order', required=True, ondelete='cascade')
     event_registration_ids = fields.One2many('registration.editor.line', 'editor_id', string='Registrations to Edit')
 
     @api.model