BPA: How to group lines and display custom description

We have a requirement to summarize and apply custom line descriptions on our invoices. We currently do this using BI Publisher and Report Builder but wanted to use BPA and gain some flexibility.

BPA seems to offer much of what we need at the header and footer sections. However the Lines and Tax region seems very limited. I have not found any features available to control the display of the lines, such as grouping and sorting. Is there some feature I am missing?

I thought that a custom Lines and Tax view was the answer, however the template required to create such view includes line-level details which prevents the use of group by in the view to accomplish our requirement. Still, I was able to get the line sum and boilerplate text created using a custom view, but in the preview it repeats for every line on the AR Transaction due to the requirement to include "Description" column. If you remove "Description" from the Lines and Tax region of the template you receive an error that Description is required. I have also tried