Probate is complicated enough that I'd recommend using an attorney--even attorneys not familiar with probate court can find it very confusing.
You can check with the county court (in the county where her mother lived) to see if probate's been filed, or if the will (if any) has been lodged. You should also check the house title to se whether probate is necessary, and also to see if the sister has already been involved in title transfers.
Attorneys often don't charge for the first consultation--a meeting could let your friend know what needs to be done in her case and what her options are.
This answer is intended, but not promised or guaranteed, to be correct, complete and up-to-date, and is of a general nature rather than specific legal advice. This answer is not intended to be a source of advertising, solicitation or legal advice.
Your friend needs an attorney. She also needs to find out if the estate was ever probated. Check the court filings in the county where your friend's mother resided. Given the small amount of information you have provided, this is unlikely to be a simple probate and your friend cannot do this on her own.
Please note that I am answering this question as a service through Avvo but not as your attorney and no attorney-client relationship is established by this posting. An attorney-client relationship can only be established through signing a Fee Agreement and paying the necessary advanced fees.
I agree with my colleagues-please find an attorney to help and advise you.
The answer given does not imply that an attorney-client relationship has been established and your best course of action is to have legal representation in this matter.
I think you are confusing "appointed" with nominated. Appointed means the will was offered for probate and your sister was appointed by the court to serve as Executor. YOu would have had to receive notice. If probate was opened, and you werent notified, you will need to bring that up to the court, and you will most likely need an attorney.
If no probate was applied for, and there are assets subject to probate (in your mother's name) or you sister stole assets (changed them into her own name) you will need to initiate probate. If you believe the Will is forged or otherwise invalid, you would want to apply for Probate under intestacy using DE-111.
Your situation is going to get contentious fast, so you really want to have an attorney doing this and not trying to do it on your own.
The general advice above does not constitute an attorney-client relationship: you haven't hired me or my firm or given me confidential information by posting on this public forum, and my answer on this public forum does not constitute attorney-client advice. IRS Circular 230 Disclosure: In order to comply with requirements imposed by the Internal Revenue Service, we inform you that any U.S. tax advice contained in this communication (including any attachments) is not intended to be used, and cannot be used, for the purpose of (i) avoiding penalties under the Internal Revenue Code or (ii) promoting, marketing, or recommending to another party any transaction or matter addressed herein. While I am licensed to practice in New York and California, I do not actively practice in New York. Regardless, nothing said should be deemed an opinion of law of any state. All readers need to do their own research or pay an attorney for a legal opinion if one is necessary or desired.