double play in reverse?

Question
We had a play recently that confused the other team we played.  Slowpitch softball, co-ed league.  We had a runner on 1st base, 1 out.  Batter hits the ball, grounder to first baseman, he picks up the ball, tags the batter-runner.  The runner already on first base did not run, but the other team threw the ball to second base, touched the bag, then ran into the dug out.  We argued that once the first baseman tagged the runner going to first, that took away the double-play and they needed to tag the runner.  We told the runner to continue onto 2nd base which she did.  The other team, although very upset, finally agreed to continue playing but still felt we were wrong.
Did we make the correct call?

Answer
Hi Brian,

You are correct in tagging the b-r you remove the force from R1 at 1st.  Touching 2nd does nothing in this situation.  R1 must now be tagged while off the base.

I don't know why they would be upset, this is a pretty basic rule of softball, there was no force at 2nd, how can they think otherwise?

Mark