I am not a lawyer, but I have handled 4 relatives estates as executor.

My understanding you have three options:

Tell the person that did this NO, and to fix this before death. Have each beneficiary named.

As beneficiary keep the money, in my state it is yours.

Three create a major accounting headache for yourself. If you distribute the money outside of the estate, you are going to create a tax liability if the amount is over the minimum that triggers gift taxes.

As an aside one woman involved in one of the estates was told verbally that she was entitled to money from one of the estates years ago.

She may have been at one time but it was no longer in the documents. She threatened to sue, She shopped the case and no one would take it.

If they are not listed as a beneficiary and don't have other legal documents giving them a claim the money is yours to do what you want with it.

Follow your conscious.