I've been an executor twice now, first was 6 beneficiaries, second was 8.
In both cases I kept accurate records of all transactions using an excel spreadsheet, a bit like a balancing accounts .. (I used to be treasurer of several clubs and the school PTA) .. this listed all incomings and outgoings so easily showing the net position. When I applied for probate I incuded these accounts along with an estimate of how much each beneficiary would get .. after my "best guess" of the tax position. The Probate Officer congratulated me on the ease of the paperwork and the accuracy of my records .. the interview lasted less than 10 minutes !!
The tax position was slighty better than my guess (deliberately done) and once the tax was paid and the final amount reconciled I sent each beneficiery a copy of the accounts and a statement of what they would receive, and gave them 14 days to query my figures. Not a single person did and the monies were then paid out a week later.
I have kept copies of the paperwork in a file in the attic so that if anyone ever decides to query anything I can show what I did and why.
This was about 15 years ago for the last one, so things might have changed ...
HTH