occupation of base

[justcallmeblue]

Question: Where to find the rule in the rulebook that can get the answer to the following sit. This may be real simple and I just blew it after 7 hrs of umpiring.

This is a RECREATION game. The kids are in 1st and 2nd grade. There is NO INFIELD FLY RULE. There is "coach pitch" however once the coach touches the ball it is dead

Sit: Bases Loaded NO outs.

Batter pops up to 1B about 2 feet from first base. R3 on 1st starts to run, but is called back by the coach because the coach thinks the ball is going to be caught. R3 returns and is standing on first base. 1B, however, drops the fly ball then picks it up and steps on first base before the BR reaches 1B. Note: R3 who has retreated to first, is standing on 1st when 1B steps on 1st. There is no tag applied to R3 and 1B returns the ball to the Coach (now a dead ball).

Whats the call (or is there even a call) on R3?