You were correct. The specific rule depends on the exact rulebook your league uses, which you did not state. I’ll show the rules from the (international) WSBC Slow Pitch Softball Playing Rules (2018–2021):
A runner is out and the ball remains live when:
vi. they physically pass a preceding runner before that runner has ...
Because baseball teams have limited rosters, and once a player is removed from the game, that player cannot return, there doesn't seem to be a loophole here that needs to be plugged. You're free to pinch hit/pinch run with the remaining players, but there's no reason that should give you a significant advantage.
Getting on base in the first place is the ...