Have they not yet been notified directly?
When my DC were beneficiaries in a relatives will (at 17 and 14) they got notification from solicitor that he had died. I had already heard from another relative but their letters made us realise they were beneficiaries. (He was a bachelor who had cancer, so death wasn’t a surprise and there had been mention already of who might be in the will).
Within the next month they got a copy of the will and a letter outlining his assets.
We spoke at length about how ‘lucky’ they were to be in the will (they didn’t know this relative, we didn’t live close by so they had only met him once or twice, although my mum saw him regularly) and that this money would be a house deposit for them if sensible.
Fortunately we already had S&S ISAs set up so they have continued drip feeding the money into them, eldest (now 23) has also got interested in buying individual company shares.
I wouldn’t necessarily say that professional advise was needed, but then DH and I have always managed our own investments so are well placed to help.
And tell them to keep shtum yes, yes, yes - we emphasised this constantly but TBH, the kids tend to forget about the money on a day to day basis, apart from it appearing in their current account a day or 2 before going into the ISA every month. They definitely don’t “splash the cash”.
I have only ever mentioned it to 1 local friend, and that was because I knew that her DC had inheritances in trust. I trust her implicitly.
The only people I have spoken to at length are relatives whose DC were the other beneficiaries.
I often see comments on here about reckless young people pissing away inheritances and I am sure it does happen, but we used it as a basis for discussions about what money was needed as an adult, and generally involved them in managing it, which seems to have worked.