it's still your family. let him now, if he doesn't know but if he's blatantly breaking the rules then you.should report him. something people here haven't been telling you, there are things called whistle blower right basically your dad can't fire you or whoever reports him and if he does or tries too you can file for unjust firing and the whistle blower laws will protect you.

I'm assuming that you are not in a position where you can casually suggest changes to your dad. If this is the case, this sounds like a situation where you should be as minimally involved as possible because anything you actively do has consequences that will bite you in the butt. I would quit ASAP, but you can still let your coworkers know that you support them and will testify to the conditions if needed. I would not tell your dad that your coworkers are planning on reporting him, because he might take it out on them. You are stuck with your dad for the rest of your life, so you shouldn't actively conspire against him either. If your dad asks you upfront, then you can offer some constructive feedback on what needs to change. (And if/when you inherit the company, you will know what to do differently!)

How to be unemployed, lose your family's trust and faith, and your chances of taking over the family business in one easy lesson. Hope you didn't need that job or expect any help from your family after this. You should move to California. There are lots of snowflake liberal idiots there, they can be your new family. You can be their hero!

Nothing wrong with that. Family or not, if the rules aren't being followed, it should be reported.

Everyone has to follow the laws. Family or not. Law is the boundary you do not break.