[CecilOne]

A couple people responded to fragments of my post, but it must be viewed in its entirety to apply (like the rule book); so here it is again:
" batted ball in flight or dribbling near the line or wherever else is not foul until it meets one of the foul ball criteria.

We have concluded in at least two other topics that the B to BR transition happens even though the batted ball does not end up being a fair batted ball; because it is not foul until the foul ball criteria apply and because it must be for the application of rules to make sense.

In this OP, the player who batted the ball, now the BR, interfered with F3 trying to field the batted ball, so the player who interfered is out, any other runner(s) return. "

I don't get calling dead ball if you don't see the play as INT. An incidental collision does not cause a dead ball. Let's ignore the UC possibility, because that would need a separate topic.

Also, it is a "play" for a fielder to go after a ground ball in foul territory because it prevents it from going fair; stops progress of BR/R, etc.