SQL Convienience model or custom abstract model?

[Borax Man]

Sorry about the repeated questions, perhaps I should get a book.

In this instance, the one view, that is, the screen will display information from all three tables (a complaint will appear, with batch and product details), so I should make the necessary columns from "Batch" and "Product" be columns in the Complaint model, and just have that one model retrieve all the necessary information, correct?

I do have one last (for now) question, which may not suit this thread.

What is the best way (or where can I find documentation to that effect), for implementing QSqlRelation like mapping for Abstract models? That is, I wish for the Batch, to have a combobox listing all available batches the user can choose from. With the convienience classes this is easy, but I'm assuming that the abstract table model has no such support, and I must do this myself?