Thanks everyone for your help, including my adagio consultant ;o)
The solution that works for us will be to have a style spec A (suppress) for the majority of our items and a style spec B (no suppress) for an item called BLANKL, which we'll use when we need to spread out our invoice information.

I wasn't aware that an item will print a blank line even if the item line# is blank/empty/unfilled when in "do not suppress blank" mode, otherwise that would have been a perfect solution for us.

The invoice specifications now make a little more sense to me when seeing Detail line A,B,C...! Andrew, I'll do a Invoices Designer refresher as well...
Karin