Hi guys,

I'm building a module that copies a whole invoice from one database to another the moment the user clicks on a button. I have a working concept, as long as there is one line (one product) on the invoice. 
The code:

# Get all ids from all taxes in the current database
tax_ids = []
for tax_id in self.invoice_line.invoice_line_tax_id:
    result = tax_proxy.search([('name', '=', tax_id.name)])
    # This means the tax doesn't exist in the target db
    if not result:
        # Create tax in target database.
        new_tax_id = tax_proxy.create({
            'name': tax_id.name,
            'amount': tax_id.amount,
            'price_include': tax_id.price_include,
            'include_base_amount': tax_id.include_base_amount,
            'child_depend': tax_id.child_depend
        })
        tax_ids.append(new_tax_id.id)
    else:
        tax_ids.append(tax_id.id)
        # Create the invoice!  
        invoice_proxy.create({
            'partner_id': partner_id, # This should be Mavi-Rent (res.contact company record)
            'account_id': account[0],
            'date_invoice': self.date_invoice,
            'fiscal_position': self.fiscal_position,
            'payment_term': self.payment_term,
            'comment': self.comment,
            'type': 'in_invoice',
            'invoice_line': [(0, 0, {
                'name': self.invoice_line.name, 
                'product_id': self.invoice_line.product_id.id,
                'account_id': self.invoice_line.account_id.id,
                'invoice_line_tax_id': [(6, 0, tax_ids)], 
                'quantity': self.invoice_line.quantity, 
                'price_unit': self.invoice_line.price_unit
             })]
        })

This however leaves me with two problems that I am unsure on how to solve:
1) The taxes are all added to a list before I do invoice_proxy.create, to create the invoice. This means that all taxes from all products will be applied. The reason that I did this before invoice_proxy.create was exactly for the same issue as problem #2.
2) This code will work if there is an invoice with one product line, but not with multiple (otherwise you'll get a singleton error).

So what I'm wondering is how should I exactly create multiple invoice_lines (with the correct taxes filled in in the many2many invoice_line_tax_id) in this .create function?

Regards,
Yenthe