Question was would there be a reason why a POA would not want to share info.
Just because clear terminology is important, let's look at the term "POA." It is an acronym that stands for "power of attorney." A power of attorney is a
document that gives one person (the agent or attorney-in-fact) authority to deal with third persons on behalf of another person (the principal). Let me emphasize that
a POA is a document. It is not a person.
With respect to a trust, the person who makes the trust (in this case, your mother) is called the trustor or settlor. The person who handles the assets that are part of the trust is called the trustee. It is
not "a POA."
With that said, if a person doesn't want to share info, of course there is a reason. There is a reason for everything.
My mom started all this suspicion as she is calling the kids who are not POAs and saying the POAs are stealing from her.
Then she should call the police.
I saw her last week and she did not know her POAs are acting without her knowledge and thought only when she was incapacitated. She tries to ask but is told not to worry.
She "tries to ask" or she actually does ask?
It would be
very helpful if you had answered this question:
Does your mother have any cognitive issues such as dementia or Alzheimers?
shouldn't the first alternate (my brother) for my DAD be taking over?
Not sure what you mean by "first alternate."
Do we first need to have my mom diagnosed as incapacitated and then legally my brother can take over as my dad's POA?
Seems to me that you ought to be consulting with an attorney who handles elder law matters about several things, including the possibility of establishing a conservatorship or conservatorships for one or both of your parents.
The alternative is to have a dialog with your sister whom you seem to suspect is engaging in various nefarious conduct.