Static Price List to Line Items file

Hello I am using FMP 9

I have main file
Table Project
Table ProjectDesign (which stores the Descriptions Prices and Qty's
and prices relative to project)
Table PriceListDesign (stores the Prices and Descriptions and Qty's
for options to be selected within ProjectDesign)

I have ProjectDesign related to PriceListDesign by description which
brings the info via a drop down palced in a portal in the Project
Table

What I am trying to do is select a Rate within ProjectDesign or
Project and have it bring over the 5 or so line items related to that
Rate. I am not sure how to go about this I can get the list to show
up in a portal but not sure how to create a new record in
ProjectDesign to store the items... Do I loop? I know what I want
just dont understand how to get it working.

I hope this makes sense and that someone can help me.

Thank you
Toni