Odd foul situation

[howie719]

I'm the lead on 2 whistle. A1 drives into lane and is fouled while shooting from behind on B1. B2 has established a legal guarding position in the general area A1 is headed. This is the tricky part. It was my contentsion that the contact by B1 diverted A1 into B2 path. I no called this contact and we went with 2 at the line. It was a pretty decent collision as well. As expected the defensive coach called time out to ask me about the contact. He didn't like my explanation, but understood what I was saying. Any thoughts on how else this could have been handled. I.E. go with the false double foul, multiple foul because B's teammate caused the collision, or false double foul.