I am the DPOA for my mother's financial and health and am her primary caregiver. Does she still need a will or trust?

Looks like you’ve pretty much answered your own question.

Personal possessions are not normally covered by a will, unless there is something specific that you want to leave to someone. If she doesn't care who gets what and you are all in agreement then you don't need to worry.

One thing, all wills start with stating you are of sound mind, can she honestly say that? If not, I would not do this legal document, I think it opens a case of worms should anyone want to contest it.

A trust would not really apply in a situation that has no assets. It would be an expensive waste of money. And she would need to understand what it is and be able to sign.

All POAs end at death, so no one is in charge at that point. Just FYI.

I don't see where a will is needed. Other than personal possessions, she has no estate.

If she is still with it, see if there are things she would like certain people to have. When we cleaned out Moms house, we all took what we wanted. Me personnally didn't need any of Moms stuff. So I didn't care what the others took. So, if you see no problem in distributing her belongings, I see no use for a will. She has to be of sound mind to do one anyway.

A will never hurts - in this case, it will help you when you go to distribute contents with your two brothers and one sister. Though you don't foresee any issues -- there's nothing like one sibling in charge to bring out issues among siblings sometimes. It would help protect you if they find things to squabble over.

Though, if she is no longer of sound mind -- legally -- it may be a mute point, she may not be able to execute a will.