If he is not of sound mind, it is illegal to get something written and signed by anyone whom is not informed about what they are signing. Elder Abuse at it's finest. I would check his important paper's to see if he may have done something or signed something unrelated as well. He may have provided for you. It sounds like his kids only care about what he will leave for them. You also need a notary.. not Nursing Staff. I did this before my spouse was not competent to sign important information. I also have all messages come to my phone . I also worked with contractor's and they had to deal with me. My spouse would add things if needed. Protect yourself. Another thing is he would have a copy of anything done legally. If you have joint accounts, go to your bank and make sure you have a clause for accounts when he passes.