Can a third POA (Jean) act without letting the secondary POA (Kay) know that they were in fact a secondary POA?

What did your sister do that you disagree with so vehemently? Unless there was gross incompetence or she somehow screwed you over then this is all water under the bridge and IMO not worth pursuing.

First of all I am not a lawyer and you should consult one, and not take the word of anyone on any forum; it is well worth an hour of time with Elder Care Attorney or Trust Attorney. But I am now serving as POA and Trustee of Trust for my brother. Here, as I understand it, is how it works. The rules of the Trust are followed, that being Dad cannot serve as he is dead. Kay now steps up to serve (unless she wishes not to). If Kay wishes not to serve, then Jean serves as POA. This is the legal format according to the Trust and any lawyer will follow it. The only way this can be set aside is if Mom is able to make a decision. If Mom is able to make a decision she can now appoint ANYONE she wishes to be her POA, and that appointment now would negate any prior designations from the old trust. So that is to say if Mom appoints Jean as her POA today, then the entire thing with the old Trust is gone, done, doesn't matter, and no one need be told. The criteria for a lawyer is not that Mom be perfect mentally, but that she understands what she is doing, and understands that she is giving complete POA to the person she appoints. Whoever is appointed POA will have ALSO to be appointed as Trustee of Trust if there is a trust, in order to access any trust funds needed for Mom's care. The POA is to act on the wishes of the person conferring POA to them, and to act in their best interests when they cannot make decisions. It can be a grueling job, and were I you I would be glad I was not appointed IF I was not appointed, as currently I am doing the work. Again, I will tell you that I AM NOT A LAWYER and you should consult an elder care or a trust attorney to get your answer, not some old bat like me on a forum. But I am doing it, and I have had to learn from three thick books more than I EVER wanted to know, hee hee. Good luck.

I read it that per the original POA, the Agents were to act in order. First dad, then Kay, then Jean.
Jean was the third and last choice only if first dad couldn’t perform and then Kay couldn’t perform.

The authority of a POA is invalid after the death of the principal.

Is it possible that your mom signed a new POA because Jean was caring for her and mom still had the mental capacity to do so?

Parents will sometimes set up their POAs, executors etc in birth order. Oldest child listed first and youngest child listed last. Then later when a POA Is actually needed they will realize that it makes life easier if the person doing the actual caring has the POA and so they change it.

It was your mothers responsibility to give you a copy of the POA at the time she signed it. Since she is deceased you can’t ask her now why she didn’t. Even if she had given it, a new POA could still have been executed. She may have even forgotten that she had signed those. Since she didn’t share it with you, you can only speculate.

In most, if not all states, only the principal ( your mother ) can assign her authority to her chosen agent (Jean or Kay).

She is free to change this as often as she chooses. So while your mom may have changed her mind on who would act when, she had to be competent to do this and she had to execute the document.

Is it possible that #3 didn’t know there was a POA already created. Just like #2 didn’t know?

She may well have taken her mom to sign one knowing she needed it to take care of her. I can’t see where that is wrong. We advise people to do that all the time.

If in her capacity as agent under ANY POA, Jean violated her authority in some manner that was harmful to your mother, she could be held accountable.

But to what degree would depend on a great many variables.

So first of all, mom should have told #2 and #3 if she wanted them to know.

If #3 later became POA, she was under no obligation to tell #2. It was mom’s business.

But also know that if a POA stepped outside the bounds of the POA document then regardless of when they were appointed, they could be held liable.

If when you read this thread, you would give us some feedback our subsequent answers might be more helpful. I’m sorry for the loss of your parents and this discord with your sister.

1) are you saying there are 2 separate PoA documents? If so, the newer one may have precedence over any older ones but I would definitely contact an attorney. My husband and his brother are both PoAs for his mom, but they are listed in the same legal document. They understand that one doesn't not act without the other's knowledge and agreement.
2) different states will have different laws surrounding PoAs.

Again, contact an attorney as this issue may be too complicated for this forum.