An important trust question

Illinois

My step dad (not legally) is still married to his first wife, living with my mother for 35 years. He and I are in a business together. They just did a living trust. I have not seen it yet.

My question; is the trust legal as he is still married to someone else? Would it be a legal document and protect both my mother and the business or would his ex and/or his children from his original marriage (over 18) have a right to anything.

I really am trying to be sure to protect my mother and the business. They are both in their 80's at this time.

Thanks

Depends on what the trust says, but everyone is living dangerously. It could be possible that you could end up being partners with his wife and later her children (all of them). This is ridiculously poor estate planning.