Q: Is there any way to find out if my niece has legal Financial POA over her mother’s money and business affairs?

A: Each Durable Power of Attorney ("DPOA") is written differently, so we would need to know if the DPOA goes into effect immediately upon being signed or only goes into effect if the person loses mental capacity (a physician would need to certify that that's the case.) Either way, when a DPOA goes into effect, it should be recorded with the County Recorder's Office in the county in which the person lives. However, not everyone knows to do that until a bank or other company tells the agent that the DPOA must have a "FILED" stamp on it to be accepted by that company. So, if your relative filed the DPOA, you could get a copy from the County Recorder. Otherwise, there is no way to get a copy without a court intervention. No one has a right to another person's trust -- even if the other person is a parent, sibling or child.

One problem with the scenario discussed in the question is the fact that your relative put her niece on the bank account as an owner. Lawyers RARELY advise clients to put a family member on the bank account for three reasons: (1) The money is legally owned by each person named on the bank account as an owner so, if the niece has a car accident, is sued and loses, the other party in the lawsuit can take every penny out of the bank account -- because the niece's name is on the account as an owner; (2) since both people own the account, if one (say the niece) took every cent out of the bank account and spent it on a new car instead of taking care of their relative, there isn't a lot that can be done about the missing money because, legally, the account belongs to both people [side note, if someone is engaging in elder abuse -- which can be financial, physical, or through neglect, for example -- then that issue can be addressed in court]; and (3) when a person dies and leaves a bank account with one family member still listed as an owner, that family member inherits 100% of the money in that account, which frequently thwarts estate plans. So, let's say a person has two kids and their estate plan says everything should be split 50/50 between the two kids. If the parent puts kid no. 1 on a bank account then dies, kid no. 1 would get everything in that bank account PLUS half of everything else. Kid no. 2 only gets half of everything else and nothing from that bank account.