How can I deal with a sibling who is very controlling, not communicative, and won't let me fulfill my role as healthcare representative?

Oh dear. I feel for you.

Is there any way you can get the two of them round a kitchen table with a flip chart on it showing "MOTHER" at the centre, surrounding by the key questions like: day to day care; managing finances; medical and nursing care needs; advocacy; etc. and get them to concentrate on the aims? Probably not, I know it's not that easy. And even if you did it wouldn't take much for them to start throwing things, sigh…

You could write to the pair of them giving a factual account of the negative impacts their attitudes and behaviour have already had on your mother. Keep emotions and emotive terms out of it as far as humanly possible. It's possible that being confronted with the reality of the effect their failure to co-operate is having will pull them up short, you never know. I just ended a wrangle with my financial POA sister saying I didn't care how we did it, but we need a better system because the fact is, the way things are, mother isn't being bought items she could really do with - got the cheque this morning, hasn't solved the system issue but it's a start.

And in your case the fact is that your mother needs skilled care and isn't getting it; needs non-exhausted constant attendance and isn't getting it; needs proper maintenance of her living environment and it isn't being done; your sister is duty-bound to communicate with her siblings and isn't doing it; you're duty-bound to supervise her health care and you can't do it; you're all required to co-operate in caring for your mother and it isn't happening. Your tone can sound as pissed-off as you like, but try not to sound tearful or accusatory - you're aiming for "unimpressed." I wouldn't at this stage be overt about your (justified) concerns for your brother's wellbeing because that's not going to get your sister's vote, and if she is dismissive he'll resent it, and you'll end up back at Square One. Whereas if you can just get more collaboration going on, he'll necessarily benefit and you'll have got the desired result by default.

Maybe that's the message for both of them - that you really don't care how you all three go about it, but you've all got to do better because it isn't working "so let's TALK please." Might get the ball rolling? Very difficult, and extremely tiresome too, actually - don't think "funny" is the word I'd use! Best of luck.

My brother resents her control and it is difficult for him to work with my sister as POA. It took months to repair a broken sink, for example, because he needed to purchase himself and submit receipts to her. I wish they could work better together.

About five years ago, we split up duties, while our mother could still be considered of sound mind, legally naming separate financial POA and health care representatives. We did this primarily because her controlling behavior did cause suspicions. There isn't any skimming going on. Her trust issues have nothing to do with me or any of my decisions. That's just the way she's built, so to speak. It is funny that most people seem to not be able to get their siblings to pitch in at all, but in my family, we have siblings excluding each other, isn't it?

When you describe yourself as "healthcare representative" do you mean that you also have POA? Were you formally appointed as such in some other way? Or is it just that that's the part you have hitherto been playing in your mother's care?

What does your brother think? What does he say about what support he needs?

In addition to the costs of facilities being about $8,000 per month, keep in mind that this $8,000/month does NOT cover: monthly insurance premiums (Medicare B, D, and supplemental ins), doctors' visits, prescriptions (AND the facility may require you to purchase meds from their pharmacy...at higher cost), clothing, shoes, walkers, lift chairs, replacement underwear/socks when the facility laundry loses them, etc. There are LOTS of costs that are above and beyond the typical $8,000/month cost.
Also---people can be evicted from memory care facilities (I have a friend who is on their 3rd facility for their parent.....). Better to keep your mom at home as long as possible. And don't "get her name on a list" because that only helps keep the facility full---it doesn't help your mom, WHEN your mom needs it.

This sounds suspicious to me. Why would she not want to take the time to report on her actions? Maybe because she is doing things that you wouldn't agree with......especially in the financial area. I would definitely NOT let her do it all, because she may be keeping track of her hours and deduct all of that time from the estate! If she has full POA, depending on how the POA is worded, the POA can be reimbursed for their time! Please have an attorney look into the particulars. It is not impossible to re-write the POA so as to keep things more fair.
I don't know the financial situation, but you should take a survey of costs of the Memory Care facilities in your area---be prepared for shock, these places typically are about $8,000/month. It may be needed at some time, but for sure, your Mom deserves to have her assets pay for her care, NOT for a possible skimming by the POA.

I may have boiled it down too simplistically.malthough I travel two,hours to go most doctors office visits with my mom and have not been allowed to be part of any of the companion selection, it is my brother and his survival that I am worried about.

She may feel the geriatric manager request is a cop-out, so she has taken over. GM's are not hands on, they are paper shufflers and a dementia patient needs daily, sometimes hourly and later constant supervision. They don't go with the patient to MD visits and that is a critical need area. Maybe she thought you dropped the ball somewhere, hired the wrong companions or something like that. Maybe she just feels guilty and wants to do more. Either way, let her do it all and be there when she burns out. If the caregiving is dividing the three of you, it may be time to look at Memory Care facilities.