Private visits to the UK in one of the many secure homes the RF own is easily arranged.
The problem will be trust that H&M won’t monetise that connection or anything they experience or observe.
The worry will be after a week at Balmoral you’ve just provided chapters 1-5 for Spare 2 on KC’s health, how many sausages were served per guest, who got the best bedrooms, how people were guarded with H&M and so on…
H just hasn’t grasped how damaging his revelations have been because he can’t prove he’s “now” trustworthy without his family taking the risk that he’s telling the truth he can be trusted (given his truth is a very nebulous concept).
It’s not even that there was a one off situation. He’s spent 5 years having a public feud with his family - so the question they are bound to ask is what has changed?
If the answer is money (or lack off) then I’d say they will be even more wary if contact for risk of being used as content fodder.