Helping a Fellow Vet with Disability Claim : Veterans

I’m trying to help a fellow Veteran with their disability claim. They currently have a %, however, as a Vietnam Veteran, I am quite confident they rate more than the 30% they’ve been rated in the recent past.

This Veteran has completed and signed the required VBA-21-22A form naming me as their Personal Representative (not Registered Agent nor Attorney). I’m looking to be able to upload this and other documents on the Veteran’s behalf, however, I do not see how I can do so on any VA.GOV site.

Does anyone here have any knowledge and/or experience with this, or point me in the right direction?

Thank you.