Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
This is an extremely complex matter and unless you are an executor or residuary legatee frankly you do not have a leg to stand on in this matter unless there has been a misappropriation of funds in which case the matter should be referred to the Procurator Fiscal. If this matter is really serious you should engage a solicitor to act as your agent, but frankly you are on a hiding to nothing.
I am so sorry to have to rain on your parade.
The residuary legatee is the person or organisation which receives the remainder of a deceased person's estate once all Inheritance Tax etc and specific legacies are distributed.
You should read the Scottish Government's guidance on deceased persons which you can find here:
If there has been, as you intimate, some misappropriation of funds or some dubiety over the will you should seek advice from the Procurator Fiscal and Police Scotland. As I have already told you it may be necessary to instruct a trusted, local agent in this matter.
Scottish wills only require one witness to their signature, unlike England where under the Wills Act, 1813, passed in the Nineteenth Century, require two. However the witness to a will cannot be a beneficiary. There is an old chestnut regarding two advocates walking down the Royal Mile from the Court of Session. They represented opposite sides in an inheritance dispute. Said one to the other, 'You know unless we are very careful there is a great danger here of the funds being frittered away amongst the beneficiaries!' That little anecdote was told to me by a Crown Agent many years ago.
Thank you for your support.