"The letter from the Lord Chancellor(or whoever it was) to the official representatives of the King in this country, was simply a reminder of where the boundaries are, because PH seems unsure what they are himself"
That is exactly it, as M0nica says, and no more.
It is in no way an indication of family relationships, it is merely a reminder that Harry and Meghan are not working Royals, not part of The Firm. They are, of course, still family members and the family should be allowed to sort out their differences (or not as the case may be) away from the glare of publicity.
Of course, Meghan and Harry may see things differently but that is the situation. They do seem to need constant publicity which is the opposite of what they claimed when they left this country. I hope the press leave them alone for the sake of their children at least.