Hey Lewis
Got an email notification about your bump... did you see my last message?
1. Your SADL query needs to be bound at the invoice item level so you get repeating lines of the invoice (I believe this is your requirement)
2. You need to have an association back to your CustomerContract BO which you populate via script
3. You need to use ToParent when navigating the SADL query (see my screenshots)
Cheers
Brad