Hand scribe changes to a boarding pass is unusual. Most ports reprint boarding pass after seat changes. There may not be an official record of this change. But India is India:- who you know means everything.

Airlines generally consider all Business seats as equal. With individual reservations it needs a BA person looking at the seats / names on a computer screen to realize 2 people are traveling together.

Suggest you put your issues and concern on exit row compliance in writing to BA, together with a print of your boarding pass.