[FIX+IMP] account_payment_order: 2 things:

* IMP: prevent deleting a move-line that is linked to a payment order line
* FIX: better filtering of move lines already included in open payment order

account_payment_order/models/account_payment_line.py

@@ -27,7 +27,8 @@ class AccountPaymentLine(models.Model):
         related='order_id.state', string='State',
         readonly=True, store=True)
     move_line_id = fields.Many2one(
-        'account.move.line', string='Journal Item')
+        'account.move.line', string='Journal Item',
+        ondelete='restrict')
     ml_maturity_date = fields.Date(
         related='move_line_id.date_maturity', readonly=True)
     currency_id = fields.Many2one(

account_payment_order/wizard/account_payment_line_create.py

@@ -112,9 +112,11 @@ class AccountPaymentLineCreate(models.TransientModel):
                 ('debit', '>', 0),
                 ('account_id.internal_type', '=', 'receivable'),
                 ]
-        # Exclude lines that are already in a non-cancelled payment order
+        # Exclude lines that are already in a non-cancelled
+        # and non-uploaded payment order; lines that are in a
+        # uploaded payment order are proposed if they are not reconciled,
         paylines = self.env['account.payment.line'].search([
-            ('state', '!=', 'cancel'),
+            ('state', 'in', ('draft', 'open', 'generated')),
             ('move_line_id', '!=', False)])
         if paylines:
             move_lines_ids = [payline.move_line_id.id for payline in paylines]