Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first
What is the wording that makes you think that the signature is essential?
If Probate has been obtained then it is a public document - if the executor will not provide a copy you can get one here
It is usual to get all the residual beneficiaries to sign off on the accounts to prevent further problems - but it would be highly unusual for any such requirement to be contained in the Will.
Assuming that it is not in the Will then the way around it is for the Beneficiary to be given three weeks to raise any specific challenges to the accounts, and that in the absence of a response it will be assumed that there are no challenges and the monies distributed accordingly
Please ask if you need further details
It has nothing to do with this Will whatsoever
If every beneficiary and Executor agrees then yes a Deed of Variation is possible - what is not possible is a legal challenge by the beneficiary causing the problems
Not unless there is some very odd wording in the Will