Can you sit down with their parents and have a discussion on why the kids are angry,what you can all agree on as 'house rules',and everyone...dad kids ,yourself....speak together on consequences? Whenever kids are involved...it is best to know how society will respond to their behaviors as adults and closely as possible stand within that range of response .Because alot of young adults get into society being oblivious as to the consequences of their actions.It'd be essential to have a chat with dad on what he expects from the kids and from your interactions.Sounds like there is alot of negativity...in that none of the adults are supportive of one another.Can you bring up that irregardless of the differences the adults are having...it is essential all adults be onboard with expectations/responses regarding the kids?I'll tell you this...if I were in a situation where my lover/significant other had kids who struck me ....and they did not step in and be an adult...I would question the validity of my place in their life.Beyond that...I'd have to leave.If a kid "hit" me and their parent didn't handle it...for everyones safety ...I'd roll on out.I couldn't contain myself.lol