Thank you for your feedback.
We need some more details to understand your suggestion better. Can you please help us by answering the following questions?

Are the attachments from a posted voucher/journal that you want to see from the trial balance when drilling to the detail?
Are these new attachments added to the trial balance?  If yes, at what level? At the account balance level? 
Are these attachments added on the trial balance list page or on the trial balance that can be created from Financial reporting?

We would appreciate additional detail on your expectations.
 
Sincerely,
Kristi Slininger, PM
Microsoft