Hello Kristie, and welcome,
That sounds like the "missing detail" problem - although without a sample report and model I can't be certain.
As long as it's no more than 100 lines you need, then there's an elegant easy fix in one model, in v12.
Otherwise it's manageable, even in earlier versions or with bigger data, using two or three models.
There's a free tool to anonymize your data at blog.greenbar.info - if you can use that and post the report here or email me I'd be happy to have a look.
After a couple of emails with Olly I found I needed to change my final line to a footer, the area I needed to capture multiple lines of data to my detail template and the remaining append until I got to my header.
In the email Olly commented " I've not found anything in 10 years that can't be modelled in Monarch" and I agree.
My management has tried to take this tool away from me. Just last year I finally got upgraded from version 3 I think, to 11.