So I'm sitting back here in Cali getting ready to wave bye bye to 2 wastes of air.
Take this for what it's worth but I know 'someone in the entertainment field' who told me months ago that California had apparently been a 'big disappointment' for HAM. Sure, they were originally welcomed with open arms, but the 'top tier of entertainment society' (TToES) that they expected to be a part of faded away after they realized that either they weren't going to make money off of HAM and/or that HAM had a very different idea of 'who they were and where they belonged' than the TToES did. TToES may like royalty, but they aren't going to treat them 'as royalty' IYSWIM. Your place in the TToES is pretty much based on your 'numbers', not who your forebears are. So HAM were pretty much in the B and C crowd, not the A list.
So my opinion is that they feel that returning to the UK, where there is a monarchy & a peerage, will put them back in the 'top tier' merely because of H's 'rank'. But again, I'm an American so what do I know about that.
I do think that KC is taking a 'wait and see' attitude when it comes to their involvement with the RF's 'get togethers'. So Xmas, Oct at Balmoral, and the like will evolve as time goes on. But I do think it'll be minimal and as much as possible be 'private' and not involve W&C. I expect this Xmas will be one that they 'choose to spend with Catherine's family' if there is any hint that HAM will appear in any way. Maybe it's time that that decades old tradition is ended. KC wants a slimmed down and more 'budget conscious' monarchy, so perhaps 'command attendance' at Sandringham for Xmas should be the first to go. I'm sure there are quite a few members of the RF that would be happy to see that end so they can spend the time with their own extended families.
PS, if HAM aren't invited I expect them to say they want to 'spend Xmas with Doria'.