Can a patient sign for consent for treatment if the patient has a POA?

Most people in NHs are on some level where they cannot discuss finances. I would think before you spoke to these residents you would talk to someone in authority that would give you the contact info of who is handling the residents finances. A Dementia/ALZ and psych patients are not able to sign legal documents.

The patient would be responsible for the bill no matter who signs, a POA does not assume financial indebtedness for the person, only the ability to advocate, get info, make decisions, buy and sell assets on behalf of. Not personally become responsible financially, thankfully, as who in their right mind would become a POA for anyone.

If the patient is competent, then the patient can sign. It is in your company's and the nursing homes' interest to take reasonable steps to ensure that anyone they are entering into a contract with is legally able to form a contract. If later it is demonstrated that the service user was away with the fairies and obviously not competent, then your company and/or the nursing home will have a contract that is not worth the paper it was written on.

You should be trained in ensuring that your service users are receiving all the information they need, and able to process it, in order to agree to these terms. Aren't you?

If they are competent, they can.