Initial jump ball tied up by THREE players...

[Lotto]

Here's something that happened this weekend. On the initial jump, three players tied up the ball---A1, B1 and B2. Clearly we have a new jump ball with A1 and one of B1 or B2. The question is, who decides?

(In the actual game, which was GJV, A1 was about 4'6", B1 was about 5'2", and B2 was about 5'10". The referee told A1 to jump against B1 so it wouldn't be completely absurd because of the difference in height.)