My dh has POA over his mum (his dad recently died too and he had it for him). Luckily, everyone (he's the youngest of 4) agreed he was to be the ONE to have it. Now he does discuss everything with his siblings but ultimately, what he says goes.
His brother is a bit greedy, "why don't we all take £500 and say it was an Xmas pressie?" - ummm no - the most dad and mum ever gave was £40 and even then, it's up to mum to decide
His older sister is "looking after" the jewellery and will share it out. Ummm no, my dh has ultimate decision - oldest sis has 3 kids, bro has 2, other sis has 4 and we have 1. LONG time ago pa in law said to share between HIS children. So jewellery goes between 4 adult offspring. You can bet your left tit that if sis in law only had 1 child it would go between siblings - you know?
What sickens me in the whole care home (she has dementia, munchausens and a form of anorexia (which she is kind of forgetting about now) ) debacle is that my dh and his siblings had a crap, penniless upbringing. They were the kids left at school on school trip day (before the days of "no child left behind") - they had a card on their birthday etc etc whilst his parents bought their council house and struggled for years. Now it has to be sold to pay for her care and will be spent til there is £23k left. Yet if they hadn't bought it, had paid the rent and actually enjoyed life and been able to afford clothes, food and holidays, it would all be paid for. Grrr.
Such a shame you have to risk your relationship with your sister.
Lastly, my ma in law just uses the home phone to ring us, and we can just ring the desk and they'll get her.