Shalom dear Rabbi,
Question:Beit Din for one guerim, may have two rabbis relatives (siblings, cousins, father and son etc ..)? even though Dayanim 2 ?, the conversion is valid?
This question is a serious question and should be discussed with a Bais Din that is qualified and recognized to do geirus, and I can only write to you in theory.
The Bais Din for geirus has to comprise of three dayanim that are kosher for a monetary din torah, meaning that they cannot be relatives. Regarding b’dieved if there weren’t three dayaniim there for the milah and or tevila, b’dieved there are different opinion if it is kosher or not. For the kabalas mitzvos though, there must be three kosher dayanim there, or it isn’t valid.
If you need help finding a Bais Din to talk to, let me know.
Shulchan Aruch and Rema Yora Deah 268-3, Shach ibid 9.