My Partner's Great-grandpa Is Being Hidden From Her After Suffering A Medical Event. She Was Always Told She Was In Charge Of Everything In The Event Something Happened To Him. Is There Anything Legally We Can Do?

Hello all, and thanks in advance for reading and any possible advice, my partner(F28) and I(M33) are very lost right now and are not even sure there is even anything we can do legally at the moment.

My partner was raised by her great-grandparents. Her great-grandma passed away in 2016 and she has kept a very close relationship with grand-grandpa (GG from here on) since then. I will be honest, the family dynamic is fairly odd, as he is not her biological GG. He does (did?) have an estranged daughter who my partner had never even met. Again, confusing, but not my partner's grandmother. Nevertheless, she was always told that when his time came she would inherit all his belongings (car, condo, bank accounts, etc). He is 86 years old and until recently was in good health. We see him 5-6 times a year for dinner or just to hang out, etc. He texts and calls weekly as well (this is important later). He never explicitly showed partner any sort of will or POA information, but had it hanging in an envelope on his fridge the entire time I've known him and he was explicitly clear that my partner was to be in charge of everything should something happen to him.

So back on Thanksgiving, partner and GG exchanged text messages back and forth as GG was visiting his girlfriend in a different city. December rolls on and texts/calls become unanswered from GG. Christmas Day, GG finally answers his cell phone. He is in a hospital but very confused and unaware where he is. He knows he is speaking to my partner, but cannot provide any information at all as to what has happened or where he is. Distraught, my partner reaches out to his estranged daughter and she confirms that he is in a hospital, will not be returning home, and she is now his POA and everything is now hers as GG took my partner out of the will back in May. Estranged daughter claims GG was upset with my partner and removed her from everything because "she abandoned him and hadn't talked to him in months" which simply is not true. I myself went and jumpstarted his car a few days before Thanksgiving and have been out to dinner with him multiple times in the past year. Anyway, I digress, she will not tell us where he is at. We have called every hospital/rehab in our area and they all claim they do not have him. We are pretty sure he is at one specific hospital, but they deny he is there. We assume estranged daughter somehow put him on a list to not contact (Is that even a thing?). Her calls to his cell phone also go straight to voicemail, but his neighbor has talked to him, so we are fairly sure the estranged daughter has blocked my partner's number from GG's phone.

On top of this, my partner always had spare keys to his condo and car. She went a few times looking for any legal documentation and could not find anything, again assuming estranged daughter took/hid it. She also knew where the safe deposit box key was, and again is missing. A few days later, she went back, and the locks were changes and his car was gone. She went to their bank, and while she is indeed still the beneficiary on GG's savings, checking, and lockbox, she cannot access the accounts unless GG is deceased. We assume estranged daughter has access to these accounts through GG's debit card as well.

This is not really about the money, inheritance, etc. My partner is going crazy not knowing what happened to him and not being able to see him. I am wondering if there is even anything legally we can do here to first of all find the man. Of course, should we find out the daughter is misusing his funds we would proceed with that in time but I am worried if his does pass it will be far too late for any meaningful resolution and for my partner's mental health. GG has been like a father to her for her entire life and is a very sweet and generous man and we know he would be upset if he knew she was being locked out.

There is a ton of information here, and I likely left quite a bit out, I will clarify anything if necessary. Thank you for any input!