Join table and invoicing solution

Hello everybody!

I am writing from Italy and this is my first post.

I was trying to create my first invoicing solution..

this is the problem:

i have created a many to many relationship (red table occurrences in the relationship graph) because to every customers are associated many items,and the price of these products is specific (=can be different) for each customer. This works fine; the join PRICE table is populated with a script associated to a button.

in the INVOICE table, it should be placed a portal to create records into the related INVOICE LINES table.

The fact is that I do not not how to relate the INVOICE and INVOICE LINES occurrence tables with the join table(PRICES), in a manner that, when I select ,for example, the customer n°1 by using a "drop-down list" placed in the invoice layout, a "conditional value list" placed into the portal will show only the products related to the customer n°1,and the associated price which is saved in the PRICE join table will appear.

i have enclosed a file sample.Only the creation of the join table works.I am missing the other part, because i am not able to come up with a solution.

someone can help?

Many thanks in advance

stefano

AN_INVOICING_SOLUTION-BASIC_CONCEPT.zip