Can two siblings be given joint power of attorney (including medical) for another sibling?

The only person who can give you power of attorney is your brother. Is he competent to do that? Basically he would have to be able to understand what it means to allow someone else to act on his behalf.

If he is incompetent to act for himself, you could become is guardian. That requires a court order.

Is your brother's current status such that he cannot function safely living alone? Would be benefit from being in a care center? Would he agree to that?

Do you know if your brother currently has an attorney? Is he single?

So much hinges on your brother's cognitive ability at this point. Can you provide a little more detail about that?

I am so sorry for this diagnosis in your family.

Hi. He was asked to sign a consent form prior to his surgery, but the team decided then that he was not understanding what they were telling him, ruling him incompetent to sign the form; my sister signed it. We have discussed the possibility of a court order. The doctors have said he cannot live alone and care for himself at this point and would likely benefit from being in a care center. He is very cooperative and docile in his current state, and would likely do whatever he was told to do to the best of his understanding. We suspect that he doesn't currently have an attorney and he is single. We do not know if he has a will and are concerned that he may lose everything that may be needed for his current and possibly future care.

Once a person is incompetent, you pursue Guardianship via surrogate's court. That's not a cheap process. On the other hand the Social Worker can get a court order making him a ward of the state, and arrange for his care. That would be the least expensive option. He cannot sign a POA anymore, it's too late.

If he is willing to go into a care center and that would be best for him according to his doctors and your observation, then the first task at hand would be to find him a suitable center. (There are lots of articles and postings about doing this, on this site.)

If I were you I'd snoop through his papers (with his permission and perhaps with him "helping" you) to see if he has consulted an attorney in the last couple of years. If you can't locate his, consult one yourself on his behalf. It may well be that an attorney specializing in Elder Law would be your best bet. He or she can advise you how to get authority to look into his finances and to spend money on his behalf.

Whatever assets he has will need to be spent on his care. If he runs out of assets (as seems likely since he is so young and may need care for a very long time) he will need to be eligible for Medicaid. The attorney can advise you how to keep records that will be needed if/when he applies for this financial aid.

Assuming your brother has some savings or other assets, you and your sister should not need to spend out of your own pockets, but can use his money to take care of consulting an attorney, obtaining guardianship (if that is necessary) etc.

Seeing to his care and advocating for him will definitely take your time and have a claim on your emotions. It doesn't seem a good option to me for sister to provide his daily care. He needs to be were there are 3 shifts of staff to look after his needs. True, someone will have to plan his funeral. At least the cost of that can be set aside now from whatever funds you discover he has.

The big role for you and your sister is to be his advocate. And it is a big role! Best wishes to you are you undertake it.