ss brought next idea :
Maybe doesnt sit properly in this newsgroup but it is DIY.
Does anyone on here have experience of accounts with reference to finalising
a balance sheet for a Will, specifically to do with expenses.

Yes, I was an Executor. Keep a careful account of everything which has
to be paid out, every reasonable expense, all of the outstanding bills
which have to be paid out - then finally tot up and itemise every penny
which which comes in. List both sets of items on a sheet, with a final
valuation at the end.

Keep a copy of each bill and each receipt for expenses.

If it is not particularly complicated, you could do the above manually
in a simple Word document, using a calculator.

Best if you can, to have someone completely independent to double check
everything tallies and your calculation, to avoid any later arguments.
Wills often cause family arguments and major disputes, so get it right.