My dad has been in an assisted living for years. I went to visit him yesterday and he was moved to another place. His step kid is in charge.

"she made her kids in charge of my dad."

Wife could not make her kids in charge of your Dad. He had to assign the stepkids as his DPOA. And at the time, have no Dementia. Once Dementia is involved, the lawyer needs to determine if Dad understands what he is signing.

You need to find out if the steps have POA. If they do, not much you can do unless Dad is cognitive and can revoke theirs and assign you. You could also go for guardianship but Dad would need to be found incompetent to handle his own life. Its expensive but if you win, you may be able to reimburse yourself out of Dads money. Guardianship revokes any POAs.

I think, given that your father chose his step family, you may require the services of an attorney to find out what your options are. Putting an bit of money into an hour of time with an Elder Law Attorney will let you know if this is worth pursuing at all.

Before you physically go to every nursing facility in the area why don't you just call them all to see if he is in any of them?
And I would just say...Can you please tell me what room number Mr. So-n-so is in?