What happen if the beneficiary named on a life policy who was separated at the time of death wants the heir named on the will to receive that benefit?

In most cases, you can decline the payment, which will go into the estate and then to the beneficiaries of the estate. Consult with the insurance company and the executor of the estate to be sure that is what you want to happen.
In most cases, you can decline the payment, which will go into the estate and then to the beneficiaries of the estate. Consult with the insurance company and the executor of the estate to be sure that is what you want to happen.