Grand Slam ends the game?

[TriggerMN]

I read a similar topic, so I figured I'd post and see if we did it the right way.

NFHS rules, tie score, bases loaded bottom of 7th, 1 out. Batter hits a home run. Runner on 3rd touches home. Runners on 2nd and 1st DO NOT touch next base, just simply run off the field. Batter rounds the bases.

What we did: we waited to see if the defensive team wanted to appeal. Throw the pitcher a ball, he takes the rubber, steps off, then throws to third for a force, then on to second for a force. 3 outs, no runs score. However, the defensive team left the field, and we called it a single, and a one run victory for the home team.

The ball is dead once it goes over the fence. Did we do right? Should the runners on 1st and 2nd have been called out for leaving the baseline? Can the defensive team appeal? What is the correct procedure for handling this situation?