I distinctly remember Omid Scobie appearing to deny that Finding Freedom's new edition would have extra chapters.
As to whether those chapters will "reopen royal rifts," I suppose that's a matter of opinion, and at any rate, those rifts can't be "reopened" if they never closed in the first place. It's hard to imagine them not making this worse, though. Even if Harry and Meghan didn't cooperate with the new chapters, the family will never believe that they didn't.
On another note, multiple sources are reporting that Harry learned of Philip's death via a phone call from an embassy staffer, not from anyone in the family.
https://www.tmz.com/2021/05/28/prin...lls-prince-philip-death-cops-home-california/
https://www.ok.co.uk/royal/breaking-prince-philip-death-harry-24211536
TMZ isn't terribly reliable, but OK! is usually, well, ok.
I think some of the details may not be quite right, because tracking down and dealing with UK citizens in the US is the job of the British embassy in the US, not the US embassy in London, but maybe things work differently in high-profile situations. And I don't think him only learning of it an hour before the media necessarily means anything, because that could still have been very soon after it happened, and we know he was able to get on a plane before it was announced.
What seems strange to me, though, is that if this is true, no one from the family tried to call him to break the news themselves. Instead, the task was assigned to some bureaucrat. I don't know how the royals normally deal with such situations, but this suggests to me that William and Charles were extremely angry with him.