When you select products with given button, it will takes you to kanban view of product lines, where you can update qty of all product from new widget, that will make your process very user friendly and faster.
Advance payment for sale and purchase with auto adjustment of advance payment on invoice and bills confirmation sales advance payment sale advance payment purchase advance payment auto adjustment on invoice auto adjustment on payment auto invoice reconcilation auto bill reconcilation
Determine information about sales supply chain of related purchase orders and pickings related purchase received status on delivery orders
Sale order lines has list of vendors for that particular product.From that shorted list based on price and delivey date, you can select vendor, for that selected vendor purchase order will be created else normal odoo process will work.