[johnnyg08]

The best way to get rid of a "bad" rule (if the coaches think it's a bad rule) is to enforce it.

Those are the rules of the game. You should enforce it, bring it up at your plate meeting.
I suppose if they don't abide by the rules, you can maybe eject (is this FED ball?) worst case, I suppose you could quit umpiring in that part of the country.
You can call time and not continue the game until they abide. It is a rule and your job is to enforce the rules as they're written. What other rules do your partners want to fudge? Those are national rules, not state rules...unless the state sets it own rules around that type of thing. I don't know enough about jurisdictions and what rules the state can and can't change in their state. I wouldn't use liability as your argument to get them to abide on the field, but rather enforcing the rules of the game.

In your pre-game with your partner you should talk about how as a crew you will handle this type of situation. You should come to common ground before you walk on the field so you're both on the same page.

Those are my thoughts, certainly others will chime in.