Can a step-child or adopted child file for power of attorney over an incapacitated parent?

If dad is mentally competent, he can appoint you legal POA to handle his affairs while he is incapacitated. He can ask an attorney to prepare it and arrange signing. If dad wants the problems sorted out and just doesn't have the strength to do it, that might an option.

If dad is not competent and thus unable to appoint a POA, then, I'd still see an attorney to get advice on going to court and seeking power to protect him and his property. The suitability of the person applying to the court for Guardianship is weighed by the court. Some immediate family members may not qualify, based on criminal records, credit status, reliability, etc. 

Is your stepfather aware of what's going on? Were you hoping to spare him from having to deal with this? Would he normally be quite capable of taking care of things, were it not for this nasty accident putting him in hospital?

You're going to need a lawyer - it's a question of whether the lawyer talks to your stepfather (and perhaps helps him set up POA for you) or advises you on other ways to proceed.

And if there are definitely illegal and/or dangerous activities going on, yes, call the police. You don't need anyone's permission to do that.

No, You don't "file" for POA, that is given by the person who then has the Power to act as his Attorney in fact (not an attorney at law). Call the police to do a welfare check on him and tell them there are people with warrants there who are taking advantage of him. Or take a broom and sweep them out yourself.

You can't file for POA. POA is given by someone to someone else. So your step father would have to be of sound mind and see a lawyer to create this document, naming you as POA. Once someone is incapacitated (legally incapacitated, not just physically) they can no longer execute a POA.

If you don't already hold POA then your next step would be guardianship, which is a costly and long court process.

Having said that...you should call the police about the activity in the home.

Angel