Sales Invoice Creation

We need a “List of Values” dialog like “Get items from” with the following features:
It should have all items linked with the selected Customer.
It should also have Purchase order column (will help selecting the relevant item in case the item is listed for more than one PO)
while we select the item on the list, all related information like purchase order no. item rate etc. should be populated in the sales invoice form.

The purpose for this is that the person preparing invoices do not know the customer purchase order nos., he can only provide itemno and qty (which is provided by customer in periodic schedule of deliveries)
so we need to bypass the PO number feeding manually everytime we make sales invoice.