Importing multiple records from a portal in an uneditable format

[indium]

Good afternoon everyone,

I'm working on an application that generates invoices using data from a Timesheet table and a separate Purchases table.

I've created a separate Summary table which contains the Timesheet records in one portal and the Purchases in a second portal.

Often the time associated with jobs is part billed, so I've used a check box in the Timesheet portal to filter which records should be added to the final invoice (which is in a separate table).

So far, so good. I can build the invoice correctly by placing portals for the Purchases and Timesheet on the invoice layout. However, I need to be able to produce an invoice history for each job, to show how much was billed and when.

Obviously when I change the check boxes in my Timesheet layout, this globally updates the values in the Timesheet portal across all my invoice records.

What I need is a way of importing the selected data from the Timesheet and Purchases portals into the invoice layout, then 'fixing' this data so that subsequent alterations to the check boxes in the Timesheet table, to create new invoices, don't affect invoices already created.

I've tried using lookups, but these only bring in the first record from the portal, whereas I need to bring in multiple lines.

I'm sure there's a simple solution to this, but I sure can't see it!

Thank you in advance for any help.