Hi and welcome!
from your description of the problem is it correct to assume that the problem field occurs many times because the detail field(s) that it summarises occur many times BUT you are able to create a template for just the detail lines you want using the trap characters? (Effectively a trap and filter in one.)
If so, and assuming the summary line follows the detail line, your append trap needs to be flagged as a FOOTER type.
However the bigger problem seems to be finding a trap for the template that acts as a filter in the same way that the detail trap works.
I have a few ideas but they do rather depend on what the report actually looks like. Is there any chance of paosting a sample page (with changes to any any parts which are confidential) so that I can check the theories?
If you look below the message entry window in the forum you will see some buttons that add Instant UBB code. Click on the CODE button and then you can cut and past a report page into the point between the tags that are provided. (Apologies if you know this but I am assuming not simply to save time in back and fore posting.)
My initial reaction, based on my interpetation of your problem, is to see if you could use pretty much the same trap line for your footer append as for the detail template but that may be a pointless way to go.
Seing the problem 'in print' would be a great help.