The whole thing will be absolutely horrendous.
They need crisis talks all of them including Megan.
Charles should do whatever it takes to bring him back into the fold, not as a work royal if Harry/Meghan don't want that but the family fold.
Any protocol stuff/legal stuff should also be thrashed out with all of them legally advised.
Eg the money/funding..so it's all explained properly and there is no room for ambiguity or misinformation./ Interpretation.
Ask them what's their ideal and try and commit to it.
Eg live independently in USA but maybe commit to Prince's trust work a few times a year in representation/ more work that can be done from the USA.
I guess the royals would ask they stop all talking to the media on any personal subject that include the royals.
Harry and Megan free to come and go at will ,Xmas in UK etc and they visit them.
All apologise to each other, especially Charles to Harry.
Kate /. Megan apologies for the sake of their children/cousin's.
Move forward afresh.