force out with runner on the bag

Question
This situation happened in a coed slow pitch softball game.
There was one out with runners on 1st and 2nd. A ball was
hit to the shortstop. The runner on second did not move and
stayed on the base. The shortstop tagged her and touched
second. Is the runner he tagged on the base out? Should this
be a double play? Does it make a difference if the shortstop
tags the person on 2nd before or after he steps on the base?
Does the runner on second have to advance no matter what?  
Thanks

Answer
Hi Joe,

this is a very common play in softball.

R1 (on 2nd) is "forced" from the base.  They no longer can legally occupy it, so tag the runner wherever they are, step on the base, in that order, DP.

If the defense steps on the base 1st then the force is now off on R1 and they can't be legally tagged on the base.

Mark