[AtlUmpSteve]

There is no rules basis (OK, don't claim to know U-trip, but anywhere else) to have that combination. It's a "please them all" solution, but clearly wrong.

You either have a) "sorry, defense, you should know better", and R2 scores with B5 returning to the plate to complete the at-bat, or b) interference by the individual that isn't a runner drawing a throw, so that individual is out, and dead ball at the time of throw, R1 scores only if has touched home prior to the time of the throw.

Personally, I lean to (b). Don't care what excuse B5 "thought", or that is was 10U, B5 doesn't get to create this attempted play where none exists and defense had a possible legitimate play. I am told U-trip most closely resembles NFHS, and that sanction doesn't allow trickery to deceive the defense.

*****Edit to respond to RKBUmp post while typing....

The ASA interp about defense knowing the situation has been generally limited to F2 throwing to 1st to retire the nonrunner. Continuing past first and drawing a throw has been a violation of ASA 8.7-M by extension to 8.7-P (an offensive team member not entitled to run drawing a throw).