>If I understand correctly, you are presenting 2 CHILD tables below that have a parent INVOICE table. If this is correct, I have only 1 child table in my application with a field to indicate the type of *line item* this represents. When you have 2 child tables, you will find it more difficult to print invoices with line items from both child tables -- you have 1 parent table with 1-to-many relations into 2 different tables.
OK, I think this was the direction I was leaning anyways. I couldn't think of any real pressing reason to have to use two tables, but things like this are easier to change in the planning stages than after writing code.
-Paul