Open Question: Is it legal for my dad to discontinue health insurance for his kids?

My dad has health and dental insurance from his work, and we all are covered under it. I have 3 siblings ages 8,13, and 15 (I am 20) My mom is also on his insurance. My dad is bi-polar, and has issues with anger (he refuses to seek treatment) He is very emotionally abusive, and threatens to not buy food. He controls all of my mom's income. He's really hard to live with. So, this morning his latest threat is that he is taking all of us off of his insurance tomorrow. My mom can get insurance from her job, but obviously it'd take some time for the paperwork. So these are my questions: a) Can he legally take his kids off insurance? Especially the younger ones? b) Will we just not have insurance tomorrow, or is there some way to be covered during the switchover? Thanks for your help! Yeah, but three people would have to report to DSS that they suspected abuse before anyone would do anything. And my dad is pretty great at hiding how he treats us. Everyone thinks he's a great guy, but no one knows what he's like at home.