Intro
We are all sure that the Mirza family is in full control of their Khilafat business.  In terms of the election of Mirza Masroor Ahmad, we have a video from 1997, wherein Mirza Tahir Ahmad mentions Mirza Masroor Ahmad and thus gives him legitimacy.

The video
https://www.alislam.org/friday-sermon/1997-12-12.html