Why all the drama?
If, and it’s a big ‘if’, they do all come, why do we need to hear so much about it?
They could fly in discreetly, go to whichever ‘royal’ accommodation they have been offered, Harry could do his Invictus business (on his own, nothing that requires Meg’s involvement as the actual event is still a whole year away), the King could meet the family privately if that’s what he wants to do, then they could all fly back to California and it could then be reported on the news.
All this pre visit nonsense will have been released by the Sussexes.