I have 2 sister companies A and B, separate chart of accounts, same physical warehouse, same customers, different products.
Company A sells the products named 'p1' and 'p2', company B sells the products 'p3' and 'p4'.

How should I setup odoo in order to:
- have a single sale order when a customer orders products (usually the orders contain products from both companies);
- when a sale order is confirmed, I need to [automatically] generate separate invoices from A and B to that customer (if the SO contains products from both companies)?

I tried with a dummy parent company but I didn't succeed.
Thank you