Sisters (ages 90 and 94) have lived together for 40 years. For the last 4 years they have shared a house with the son/nephew. One has been taken away by granddaughter without discussing anything with the other family members, including 2 that have been most involved in the seniors day to day lives.
I think I'd bring her back to her home, take her to an estate planning attorney and execute a new DPOA removing the granddaughter.
It would help though if you explained who "we" are. What relation are you, and what is your interest?
When the emotional wellbeing is not being consideted, there must be something that can be done.
And are you trying to figure out where to put the other sister, or are you still wanting the sister who was removed returned? Please tell us more, so we can give you better answers.
I don't know of any service or court who will mandate where someone lives.