I need advice- does their daughter have legal rights to abolish POA?

My husband and I are trying to help the best way we can to an elderly couple. We'd been friends for almost 30 years. He is 90 years old with the onset of Alzheimer's and been with his wife for 56 years. She's 85 years of age with acute Parkinson's. They have a daughter who is a little slow in her thinking and a grandson of 25 who's a ward of the state (Daughter's son).Over the years I've known her as her parent's disabilities progressed she never could understand or do anything about their needs. They lived neglected and very lonely. We went to visit them often but we saw they need professional help. They asked us if they could grant us a POA so we could legally help them in every aspect they needed. We apprehensible accepted. It's being two weeks that we had placed them in a retirement home with assisted living (Guide and helped by numerous kind people and supervised by Social services - Also two weeks that we have the POA) Morning Side is a lovely place. Elegant, good service, has a "restaurant like" dining room, they serve very good food a la cart. The couple are loving it there. At least for now. They aren't lonely or neglected anymore. Their daughter has a male companion, he's dominant and a free loader. Her previous partners took plenty advantage of her, many of them took her savings and things of value. This one is hanging around (A bit more than a year) with the idea that her parents will die soon and he'll be able to collect on that price money. (I'm not exaggerating at all). He lets his opinions be heard. They have two assets. One is a small investment. Surrendering and closing this account will provide with two years of living expenses at their retirement home. The other strong asset is is the money that will come from the sale of the house. (The house was badly neglected) The proceeds of this sale will go directly into the same Trust fund which I will set up with electronic withdraws from Morning Side, their retirement home. With this money they have another 3 years of living comfortably and care. They'll have 5 years at the most to live a happier life if there isn't emergency expenses.
Since their daughter doesn't understand much of what we're trying to do securing her parents last years of life, she is angry, demanding for her rightful inheritance money. (Companion's advice) What I'm concerned about is that she will seek a lawyer's service and with that try to have annulled the Power of Attorney we have. I'm their first Agent. If she succeeds, along with her partner they will dispose of her parents money leaving them with almost nothing. If this happens her parents couldn't continue staying in their present residence. The retirement home they started to enjoy so very much. Here is where I ask for someone's advice
Does she have enough legal rights to abolish the POA? What can we legally expect?
We don't want our friends to end up on the street even though I have already arranged with the "Little Sisters of the Poor" to take them in when they run out of money. They agreed. It's a retirement home run by nuns specialized in elderly disable care, They work with the State. But first I would like them to enjoy as much as they can while they can and while we can still have control of their money that will pay for their care and happiness. Please tell me what my position will be on the matter if the daughter decides the worst. I'll appreciate very much any input. Thanks!
My best regards to all of you.
Tania