POA not acting in best interest. Any advice?

When you say squabble, do you mean you and your mom or you and your sister?

Either way, I am so sorry that you are struggling with this. Hopefully, you will be able to resolve it soon.

So, your sister has POA? Your profile says mom is in memory care. So, how are you her caregiver?

Can you clarify for us please? Thanks.

Your sibling isn’t legally required to disclose anything to you. The best thing to do is try to work things out with your sibling.

I'd get a legal opinion. I don't get the part about a sibling appointing a POA. Did mom appoint the sibling or did a court appoint a Guardian? Either way, I'd seek legal advice about your options.