While an executor cannot stop you from entering a private contract, they can refuse to cooperate by:

• Declining to provide estate documents to the funder.
• Refusing to sign the assignment acknowledgment.
• Challenging the advance in probate court.

If this happens, most funding companies will withdraw to avoid a prolonged legal battle. The practical workaround is transparency: loop the executor into conversations early, provide the advance agreement for review, and remind them that the arrangement does not diminish other heirs’ shares or slow the probate timeline.