diff --git a/addons/purchase/company.py b/addons/purchase/company.py
index 5458297a889..6ee4d0664a3 100644
--- a/addons/purchase/company.py
+++ b/addons/purchase/company.py
@@ -12,10 +12,17 @@ class company(models.Model):
              "they will be scheduled that many days earlier "
              "to cope with unexpected vendor delays.", default=0.0)
 
+    po_lock = fields.Selection([
+        ('edit', 'Allow to edit purchase orders'),
+        ('lock', 'Confirmed purchase orders are not editable')
+        ], string="Purchase Order Modification", default="edit",
+        help='Purchase Order Modification used when you want to purchase order editable after confirm')
+
     po_double_validation = fields.Selection([
         ('one_step', 'Confirm purchase orders in one step'),
         ('two_step', 'Get 2 levels of approvals to confirm a purchase order')
         ], string="Levels of Approvals", default='one_step',\
         help="Provide a double validation mechanism for purchases")
+
     po_double_validation_amount = fields.Monetary(string='Double validation amount', default=5000,\
         help="Minimum amount for which a double validation is required")
diff --git a/addons/purchase/company_view.xml b/addons/purchase/company_view.xml
index e57d15acb84..b1772a9e720 100644
--- a/addons/purchase/company_view.xml
+++ b/addons/purchase/company_view.xml
@@ -10,6 +10,7 @@
             <field name="arch" type="xml">
                 <xpath expr="//group[@name='logistics_grp']" position="inside">
                         <field name="po_lead"/>
+                        <field name="po_lock" widget="radio"/>
                         <field name="po_double_validation" widget="radio"/>
                         <field name="po_double_validation_amount" attrs="{'invisible': [('po_double_validation', '=', 'one_step')]}"/>
                 </xpath>
diff --git a/addons/purchase/purchase.py b/addons/purchase/purchase.py
index 05db716bf5f..34493ce3cda 100644
--- a/addons/purchase/purchase.py
+++ b/addons/purchase/purchase.py
@@ -45,7 +45,7 @@ class PurchaseOrder(models.Model):
     def _get_invoiced(self):
         precision = self.env['decimal.precision'].precision_get('Product Unit of Measure')
         for order in self:
-            if order.state != 'purchase':
+            if order.state not in ('purchase', 'done'):
                 order.invoice_status = 'no'
                 continue
 
@@ -122,16 +122,16 @@ class PurchaseOrder(models.Model):
         ('done', 'Locked'),
         ('cancel', 'Cancelled')
         ], string='Status', readonly=True, select=True, copy=False, default='draft', track_visibility='onchange')
-    order_line = fields.One2many('purchase.order.line', 'order_id', string='Order Lines', states=READONLY_STATES, copy=True)
+    order_line = fields.One2many('purchase.order.line', 'order_id', string='Order Lines', states={'cancel': [('readonly', True)], 'done': [('readonly', True)]}, copy=True)
     notes = fields.Text('Terms and Conditions')
 
-    invoice_count = fields.Integer(compute="_compute_invoice", string='# of Invoices', copy=False, default=0)
-    invoice_ids = fields.Many2many('account.invoice', compute="_compute_invoice", string='Invoices', copy=False)
+    invoice_count = fields.Integer(compute="_compute_invoice", string='# of Bills', copy=False, default=0)
+    invoice_ids = fields.Many2many('account.invoice', compute="_compute_invoice", string='Bills', copy=False)
     invoice_status = fields.Selection([
-        ('no', 'Not purchased'),
-        ('to invoice', 'Waiting Invoices'),
-        ('invoiced', 'Invoice Received'),
-        ], string='Invoice Status', compute='_get_invoiced', store=True, readonly=True, copy=False, default='no')
+        ('no', 'Nothing to Bill'),
+        ('to invoice', 'Waiting Bills'),
+        ('invoiced', 'Bills Received'),
+        ], string='Billing Status', compute='_get_invoiced', store=True, readonly=True, copy=False, default='no')
 
     picking_count = fields.Integer(compute='_compute_picking', string='Receptions', default=0)
     picking_ids = fields.Many2many('stock.picking', compute='_compute_picking', string='Receptions', copy=False)
@@ -145,7 +145,7 @@ class PurchaseOrder(models.Model):
 
     fiscal_position_id = fields.Many2one('account.fiscal.position', string='Fiscal Position', oldname='fiscal_position')
     payment_term_id = fields.Many2one('account.payment.term', 'Payment Term')
-    incoterm_id = fields.Many2one('stock.incoterms', 'Incoterm', help="International Commercial Terms are a series of predefined commercial terms used in international transactions.")
+    incoterm_id = fields.Many2one('stock.incoterms', 'Incoterm', states={'done': [('readonly', True)]}, help="International Commercial Terms are a series of predefined commercial terms used in international transactions.")
 
     product_id = fields.Many2one('product.product', related='order_line.product_id', string='Product')
     create_uid = fields.Many2one('res.users', 'Responsible')
@@ -304,9 +304,15 @@ class PurchaseOrder(models.Model):
         return self.env['report'].get_action(self, 'purchase.report_purchasequotation')
 
     @api.multi
-    def button_approve(self):
+    def button_approve(self, force=False):
+        if self.company_id.po_double_validation == 'two_step'\
+          and self.amount_total >= self.env.user.company_id.currency_id.compute(self.company_id.po_double_validation_amount, self.currency_id)\
+          and not self.user_has_groups('purchase.group_purchase_manager'):
+            raise UserError(_('You need purchase manager access rights to validate an order above %.2f %s.') % (self.company_id.po_double_validation_amount, self.company_id.currency_id.name))
         self.write({'state': 'purchase'})
         self._create_picking()
+        if self.company_id.po_lock == 'lock':
+            self.write({'state': 'done'})
         return {}
 
     @api.multi
@@ -319,14 +325,11 @@ class PurchaseOrder(models.Model):
         for order in self:
             order._add_supplier_to_product()
             # Deal with double validation process
-            if order.company_id.po_double_validation == 'one_step'\
-                    or (order.company_id.po_double_validation == 'two_step'\
-                        and order.amount_total < self.env.user.company_id.currency_id.compute(order.company_id.po_double_validation_amount, order.currency_id))\
-                    or order.user_has_groups('purchase.group_purchase_manager'):
-                order.button_approve()
+            if order.company_id.po_double_validation == 'one_step':
+                order.button_approve(force=True)
             else:
                 order.write({'state': 'to approve'})
-        return {}
+        return True
 
     @api.multi
     def button_cancel(self):
@@ -381,13 +384,18 @@ class PurchaseOrder(models.Model):
 
     @api.multi
     def _create_picking(self):
+        StockPicking = self.env['stock.picking']
         for order in self:
             if any([ptype in ['product', 'consu'] for ptype in order.order_line.mapped('product_id.type')]):
-                res = order._prepare_picking()
-                picking = self.env['stock.picking'].create(res)
-                moves = order.order_line.filtered(lambda r: r.product_id.type in ['product', 'consu'])._create_stock_moves(picking)
-                moves.action_confirm()
-                order.order_line.mapped('move_ids').force_assign()
+                pickings = order.picking_ids.filtered(lambda x: x.state not in ('done','cancel'))
+                if not pickings:
+                    res = order._prepare_picking()
+                    picking = StockPicking.create(res)
+                else:
+                    picking = pickings[0]
+                moves = order.order_line._create_stock_moves(picking)
+                moves = moves.action_confirm()
+                moves.force_assign()
                 picking.message_post_with_view('mail.message_origin_link',
                     values={'self': picking, 'origin': order},
                     subtype_id=self.env.ref('mail.mt_note').id)
@@ -523,7 +531,22 @@ class PurchaseOrderLine(models.Model):
                         total += move.product_uom_qty
             line.qty_received = total
 
+    @api.model
+    def create(self, values):
+        line = super(PurchaseOrderLine, self).create(values)
+        if line.order_id.state == 'purchase':
+            line.order_id._create_picking()
+        return line
+
+    @api.multi
+    def write(self, values):
+        result = super(PurchaseOrderLine, self).write(values)
+        orders = self.filtered(lambda x: x.order_id.state == 'purchase').mapped('order_id')
+        orders._create_picking()
+        return result
+
     name = fields.Text(string='Description', required=True)
+    sequence = fields.Integer(string='Sequence', default=10)
     product_qty = fields.Float(string='Quantity', digits=dp.get_precision('Product Unit of Measure'), required=True)
     date_planned = fields.Datetime(string='Scheduled Date', required=True, select=True)
     taxes_id = fields.Many2many('account.tax', string='Taxes', domain=['|', ('active', '=', False), ('active', '=', True)])
@@ -542,7 +565,7 @@ class PurchaseOrderLine(models.Model):
     company_id = fields.Many2one('res.company', related='order_id.company_id', string='Company', store=True, readonly=True)
     state = fields.Selection(related='order_id.state', store=True)
 
-    invoice_lines = fields.One2many('account.invoice.line', 'purchase_line_id', string="Invoice Lines", readonly=True, copy=False)
+    invoice_lines = fields.One2many('account.invoice.line', 'purchase_line_id', string="Bill Lines", readonly=True, copy=False)
 
     # Replace by invoiced Qty
     qty_invoiced = fields.Float(compute='_compute_qty_invoiced', string="Billed Qty", store=True)
@@ -572,8 +595,12 @@ class PurchaseOrderLine(models.Model):
         moves = self.env['stock.move']
         done = self.env['stock.move'].browse()
         for line in self:
+            if line.product_id.type not in ['product', 'consu']:
+                continue
+            qty = 0.0
             price_unit = line._get_stock_move_price_unit()
-
+            for move in line.move_ids.filtered(lambda x: x.state != 'cancel'):
+                qty += move.product_qty
             template = {
                 'name': line.name or '',
                 'product_id': line.product_id.id,
@@ -596,9 +623,8 @@ class PurchaseOrderLine(models.Model):
                 'route_ids': line.order_id.picking_type_id.warehouse_id and [(6, 0, [x.id for x in line.order_id.picking_type_id.warehouse_id.route_ids])] or [],
                 'warehouse_id':line.order_id.picking_type_id.warehouse_id.id,
             }
-
             # Fullfill all related procurements with this po line
-            diff_quantity = line.product_qty
+            diff_quantity = line.product_qty - qty
             for procurement in line.procurement_ids:
                 procurement_qty = procurement.product_uom._compute_quantity(procurement.product_qty, line.product_uom)
                 tmp = template.copy()
@@ -618,7 +644,7 @@ class PurchaseOrderLine(models.Model):
     @api.multi
     def unlink(self):
         for line in self:
-            if line.order_id.state in ['approved', 'done']:
+            if line.order_id.state in ['purchase', 'done']:
                 raise UserError(_('Cannot delete a purchase order line which is in state \'%s\'.') %(line.state,))
             for proc in line.procurement_ids:
                 proc.message_post(body=_('Purchase order line deleted.'))
@@ -722,6 +748,15 @@ class PurchaseOrderLine(models.Model):
 
         self.price_unit = price_unit
 
+    @api.onchange('product_qty')
+    def _onchange_product_qty(self):
+        if (self.state == 'purchase' or self.state == 'to approve') and self.product_id.type in ['product', 'consu'] and self.product_qty < self._origin.product_qty:
+            warning_mess = {
+                'title': _('Ordered quantity decreased!'),
+                'message' : _('You are decreasing the ordered quantity!\nYou must update the quantities on the reception and/or bills.'),
+            }
+            return {'warning': warning_mess}
+
     def _suggest_quantity(self):
         '''
         Suggest a minimal quantity based on the seller
@@ -991,8 +1026,8 @@ class ProductTemplate(models.Model):
         ('purchase', 'On ordered quantities'),
         ('receive', 'On received quantities'),
         ], string="Control Purchase Bills",
-        help="On ordered quantities: Invoice this product based on ordered quantities.\n"
-        "On received quantities: Invoice this product based on received quantity.", default="receive")
+        help="On ordered quantities: control bills based on ordered quantities.\n"
+        "On received quantities: control bills based on received quantity.", default="receive")
     route_ids = fields.Many2many(default=lambda self: self._get_buy_route())
     purchase_line_warn = fields.Selection(WARNING_MESSAGE, 'Purchase Order Line', help=WARNING_HELP, required=True, default="no-message")
     purchase_line_warn_msg = fields.Text('Message for Purchase Order Line')
diff --git a/addons/purchase/purchase_view.xml b/addons/purchase/purchase_view.xml
index 7012aedc7c6..0c82aba1a5b 100644
--- a/addons/purchase/purchase_view.xml
+++ b/addons/purchase/purchase_view.xml
@@ -175,21 +175,23 @@
                     <button name="action_view_picking" string="Receive Products" class="oe_highlight" type="object" attrs="{'invisible': ['|', '|' , ('is_shipped', '=', True), ('state','not in', ('purchase','done')), ('picking_count', '=', 0)]}"/>
                     <button name="button_draft" states="cancel" string="Set to Draft" type="object" />
                     <button name="button_cancel" states="draft,to approve,sent,purchase" string="Cancel" type="object" />
-                    <button name="button_done" type="object" string="Lock Bills" states="purchase"/>
+                    <button name="button_done" type="object" string="Lock" states="purchase"/>
                     <field name="state" widget="statusbar" statusbar_visible="draft,sent,purchase" readonly="1"/>
                 </header>
                 <sheet>
-                    <div class="oe_button_box" name="button_box" attrs="{'invisible': [('state', 'not in', ('purchase', 'done', 'cancel'))]}">
+                    <div class="oe_button_box" name="button_box">
                         <button type="object"
                             name="action_view_picking"
                             class="oe_stat_button"
-                            icon="fa-truck">
+                            icon="fa-truck" attrs="{'invisible':[('state', 'in', ('draft','sent','to approve')),('picking_ids','=',[])]}">
                             <field name="picking_count" widget="statinfo" string="Shipment" help="Incoming Shipments"/>
+                            <field name="picking_ids" invisible="1"/>
                         </button>
                         <button type="object"  name="action_view_invoice"
                             class="oe_stat_button"
-                            icon="fa-pencil-square-o">
+                            icon="fa-pencil-square-o" attrs="{'invisible':[('state', 'in', ('draft','sent','to approve')),('invoice_ids','=',[])]}">
                             <field name="invoice_count" widget="statinfo" string="Invoices"/>
+                            <field name='invoice_ids' invisible="1"/>
                         </button> 
                     </div>
                     <div class="oe_title">
@@ -214,9 +216,11 @@
                     </group>
                     <notebook>
                         <page string="Products">
-                            <field name="order_line">
-                                <tree string="Purchase Order Lines" editable="bottom">
-                                    <field name="product_id" context="{'partner_id': parent.partner_id}"/>
+                            <field name="order_line" attrs="{'readonly': [('state', 'in', ('done', 'cancel'))]}">
+                                 <tree string="Purchase Order Lines" editable="bottom">
+                                    <field name="state" invisible="1"/>
+                                    <field name="sequence" widget="handle"/>
+                                    <field name="product_id" attrs="{'readonly': [('state', 'in', ('purchase', 'to approve','done', 'cancel'))]}" context="{'partner_id':parent.partner_id, 'quantity':product_qty,'uom':product_uom, 'company_id': parent.company_id}"/>
                                     <field name="name"/>
                                     <field name="date_planned"/>
                                     <field name="company_id" groups="base.group_multi_company" options="{'no_create': True}"/>
@@ -225,7 +229,7 @@
                                     <field name="product_qty"/>
                                     <field name="qty_received" invisible="not context.get('show_purchase', False)"/>
                                     <field name="qty_invoiced" invisible="not context.get('show_purchase', False)"/>
-                                    <field name="product_uom" groups="product.group_uom"/>
+                                    <field name="product_uom" groups="product.group_uom" attrs="{'readonly': [('state', 'in', ('purchase', 'done', 'cancel'))]}"/>
                                     <field name="price_unit"/>
                                     <field name="taxes_id" widget="many2many_tags" domain="[('type_tax_use','=','purchase')]" context="{'default_type_tax_use': 'purchase'}"/>
                                     <field name="price_subtotal" widget="monetary"/>
@@ -292,8 +296,8 @@
                                 </group>
                                 <group>
                                     <field name="invoice_status"/>
-                                    <field name="payment_term_id" options="{'no_open': True, 'no_create': True}" attrs="{'readonly': [('invoice_status','=', 'invoiced')]}"/>
-                                    <field name="fiscal_position_id" attrs="{'readonly': [('invoice_status','=', 'invoiced')]}" />
+                                    <field name="payment_term_id" options="{'no_open': True, 'no_create': True}" attrs="{'readonly': ['|', ('invoice_status','=', 'invoiced'), ('state', '=', 'done')]}"/>
+                                    <field name="fiscal_position_id" attrs="{'readonly': ['|', ('invoice_status','=', 'invoiced'), ('state', '=', 'done')]}"/>
                                     <field name="date_approve" groups="base.group_no_one"/>
                                 </group>
                             </group>
diff --git a/addons/purchase/res_config.py b/addons/purchase/res_config.py
index b5bd8db2f71..db6006b8847 100644
--- a/addons/purchase/res_config.py
+++ b/addons/purchase/res_config.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
+from openerp import SUPERUSER_ID
 from openerp.osv import fields, osv
 from openerp.tools.translate import _
 
diff --git a/addons/purchase/tests/__init__.py b/addons/purchase/tests/__init__.py
index 28061bc088d..53b60c7dba4 100644
--- a/addons/purchase/tests/__init__.py
+++ b/addons/purchase/tests/__init__.py
@@ -1,4 +1,4 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from . import test_onchange_product_id, test_purchase_order
\ No newline at end of file
+from . import test_onchange_product_id, test_purchase_order, test_create_picking
\ No newline at end of file
diff --git a/addons/purchase/tests/test_create_picking.py b/addons/purchase/tests/test_create_picking.py
new file mode 100644
index 00000000000..5ea0b1b3bf7
--- /dev/null
+++ b/addons/purchase/tests/test_create_picking.py
@@ -0,0 +1,91 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from datetime import datetime
+from openerp.tools import DEFAULT_SERVER_DATETIME_FORMAT
+from odoo.addons.product.tests import common
+
+
+class TestCreatePicking(common.TestProductCommon):
+
+    def setUp(self):
+        super(TestCreatePicking, self).setUp()
+        self.partner_id = self.env.ref('base.res_partner_1')
+        self.product_id_1 = self.env.ref('product.product_product_8')
+        self.product_id_2 = self.env.ref('product.product_product_11')
+        res_users_purchase_user = self.env.ref('purchase.group_purchase_user')
+
+        Users = self.env['res.users'].with_context({'no_reset_password': True, 'mail_create_nosubscribe': True})
+        self.user_purchase_user = Users.create({
+            'name': 'Pauline Poivraisselle',
+            'login': 'pauline',
+            'email': 'pur@example.com',
+            'notify_email': 'none',
+            'groups_id': [(6, 0, [res_users_purchase_user.id])]})
+
+        self.po_vals = {
+            'partner_id': self.partner_id.id,
+            'order_line': [
+                (0, 0, {
+                    'name': self.product_id_1.name,
+                    'product_id': self.product_id_1.id,
+                    'product_qty': 5.0,
+                    'product_uom': self.product_id_1.uom_po_id.id,
+                    'price_unit': 500.0,
+                    'date_planned': datetime.today().strftime(DEFAULT_SERVER_DATETIME_FORMAT),
+                })],
+        }
+
+    def test_00_create_picking(self):
+
+        # Draft purchase order created
+        self.po = self.env['purchase.order'].create(self.po_vals)
+        self.assertTrue(self.po, 'Purchase: no purchase order created')
+
+        # Purchase order confirm
+        self.po.button_confirm()
+        self.assertEqual(self.po.state, 'purchase', 'Purchase: PO state should be "Purchase')
+        self.assertEqual(self.po.picking_count, 1, 'Purchase: one picking should be created')
+        self.assertEqual(len(self.po.order_line.move_ids), 1, 'One move should be created')
+
+        # Change purchase order line product quantity
+        self.po.order_line.write({'product_qty': 7.0})
+        self.assertEqual(len(self.po.order_line.move_ids), 2, 'Two move should be created')
+
+        # Validate first shipment
+        self.picking = self.po.picking_ids[0]
+        self.picking.force_assign()
+        self.picking.pack_operation_product_ids.write({'qty_done': 7.0})
+        self.picking.do_new_transfer()
+        self.assertEqual(self.po.order_line.mapped('qty_received'), [7.0], 'Purchase: all products should be received')
+
+        # create new order line
+        self.po.write({'order_line': [
+            (0, 0, {
+                'name': self.product_id_2.name,
+                'product_id': self.product_id_2.id,
+                'product_qty': 5.0,
+                'product_uom': self.product_id_2.uom_po_id.id,
+                'price_unit': 250.0,
+                'date_planned': datetime.today().strftime(DEFAULT_SERVER_DATETIME_FORMAT),
+                })]})
+        self.assertEqual(self.po.picking_count, 2, 'New picking should be created')
+        moves = self.po.order_line.mapped('move_ids').filtered(lambda x: x.state not in ('done', 'cancel'))
+        self.assertEqual(len(moves), 1, 'One move should be created')
+
+    def test_01_check_double_validation(self):
+
+        # make double validation two step
+        self.env.user.company_id.write({'po_double_validation': 'two_step'})
+
+        # Draft purchase order created
+        self.po = self.env['purchase.order'].sudo(self.user_purchase_user).create(self.po_vals)
+        self.assertTrue(self.po, 'Purchase: no purchase order created')
+
+        # Purchase order confirm
+        self.po.button_confirm()
+        self.assertEqual(self.po.state, 'to approve', 'Purchase: PO state should be "to approve".')
+
+        # PO approved by manager
+        self.po.button_approve()
+        self.assertEqual(self.po.state, 'purchase', 'PO state should be "Purchase".')