Can all the beneficiaries of a registered will change the terms of the will after the death of the testator?

Will of a testator is a document which gets permanently sealed on the day of the death of the testator; so the beneficiaries cannot change the terms and conditions as laid down in the will --- But what all the beneficiary with mutual consent can do is that they can "relinquish" their rights in favour of each other either completely or partially through a "Relinquishment Deed" in which they can change the distribution of the property and rights which they all acquire under the terms of the will -- but still the will cannot be changed though the distribution of the benefits arising from that will changes in reality.