Firstly, a POA or power of attorney gives a person the right to act as "agent" for another person (the "principal") during their life when they are incapacitated. Once someone dies, the agency ends and the POA is meaningless. Expenses of burial are an expense of the person's estate. That said, a person may not have much of an estate if they pass all their assets to people through non-probate transfers (beneficiary designations on life insurance, IRA, etc.). You say she is the beneficiary of the house but it is not clear if that was owned joint with right of survivorship (non-probate) or in his name alone (probate). At this point, someone needs to hire an attorney and/or determine if he had a will and open his estate to deal with these issues.
This is not legal advice nor intended to create an attorney-client relationship. The information provided here is informational in nature only. This attorney may not be licensed in the jurisdiction which you have a question about so the answer could be only general in nature. Visit Steve Zelinger's website: http://www.stevenzelinger.com/
The simplest solution would be for you and your siblings to hire an attorney to write a letter to the sister with the POA and ask for information about your father's estate. If you and your siblings work together and there are no disagreements among you, then one lawyer can represent you all.
The attorney will want to review all the documentation you have with respect to your father's estate, so be sure to pull all of that together.
The POA essentially became a nullity after your father passed away. However, there may be claims against your sister for misuse of that POA during your father's life. California has quite strict laws on financial elder abuse, and those laws may give your father's estate a claim against your sister for any improper decisions your sister made.
I have handled problems like this, and would be happy to speak with you about this matter at a mutually convenient time if you so desire.
I agree with Attorney Zelinger. There is no way you are going to be able to get to the bottom of this and have a reasonable chance of challenging anything that your sister may have done without a skillful probate litigation attorney. You should take all of the information you have and schedule an appointment right away. If things are as you believe, time is of the essence.
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