``` A---B---C main \ D---E---F feature1 \ \---G---H feature2 \ \---I---J feature3 ```
(sorry about the formatting here. I guess you'll have to copy & paste it to read it)
What I'm saying is that if I want to fix something in D, I do `jj new D` to create a new commit on top of D. Then I make the fix, run tests, etc., and then I run `jj squash` to amend the changes into D. The descendant commits (E through J) then get automatically rebased and the feature bookmarks/branches get updated.
I didn't follow what you about it other changes needed for updating the ancestor. Can you explain in the context of this example?