It is possible that the sworn statement, or Affidavit, of a person with actual knowledge will suffice. The person signing the Affidavit should have no financial interest in the matter.
Answers to questions on this site are not intended to be specific legal advice nor create an attorney-client relationship. Hiring an attorney is a very important process which requires a high degree of diligence as well as entering into an agreement regarding the services to be provided and the fees to be charged.
If you know the county where the cousin's estate was probated, they should have the records of the letters of administration that would have named your mother as executor. That should be sufficient since it will also state their relationship.
Carol Johnson Law Firm, P.A. : (727) 647-6645 : email@example.com : Wills, Trusts, Real Property, Probate, Special Needs: Information provided here is anecdotal and should not be relied upon or considered legal advice. Every matter is different and answers given here are general in nature and may not reflect current Florida law at the time you are reading this posting. Please contact me if you feel you need additional assistance with your matter.
Look in the county records where the estate was "raised"
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/
I would look at the probate records in the court where the estate was probated.
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.