How can we know whether someone is following parampara?

From: Gadhadhar Pandit Group

Gadhadhar Pandit Group is a group for reading Srimad Bhagavatam of Raghunath Bhatt Vrinda Counselors from Pune which consists of HG Ananta Gopa Pr (leader), HG Vamanadev Pr, HG Sri Baladev Pr, HG Sonar Gauranga Pr & Sripad Mahaprabhu das.

So on behalf of our group, we would like to ask following questions:

When can we say that somebody is folliwng the disciplic succession? What is the criteria?