infield pop fly

Question
we had bases loaded 1 out my daughter hit an infield pop fly 2nd base caught it then dropped it thought it to first base the runner had advanced slid back to first he called both runners out i am confused i have read the rule book it says nothing about if the fly is dropped so is it and out if it is dropped?

Answer
When the infield fly rule is in effect, and it was in your situation.  The batter is out regardless of whether the ball is caught.  For the rest of the players they may advance without tagging up if the ball is caught.  They must tag up if the ball is caught.

In your daughters situation, she would only be out if she were tagged while off the base.  If the ball had been caught and the 2nd base player touched the base before the runner returned, then you have two outs.

The easiest way to look at it is the IFR only effects the batter.  The runners have the option of advancing based on how the play is made