DGM (DM's Mum) died about 3 years ago. DM wasn't and still isn't on speaking terms with her siblings (one brother, one sister). My cousin (DM's sister's daughter) is the executor of the estate.
About 18 months ago the estate was settled and money distributed evenly (as far as we know). DM got a cheque and we thought that was that. Last week DM got a text message from my cousin saying some additional shares have been discovered and she was sending a cheque over. The cheque arrived today for exactly £10K. DM was pleased with the unexpected windfall, however, DF spoke to me separately to say he is suspicious that something is afoot. He questions the fact that any sale of shares split 3 ways would surely result in a non-round number being produced. He is concerned that the family are somehow conning DM of her rightful share of the additional money that has been found. He hasn't mentioned anything to DM yet as she has a tendency to fly off the handle and may cause more trouble for herself and the family by saying/doing the wrong thing in anger.
Could anyone advise on what, if anything, they can do to investigate the matter and whether it is worth seeking professional legal advice on a the matter?