VE requirement (T245299):

• As someone editing in VE, you should not be able to mistakenly break/delete parent references by attempting to edit the contents of a sub-reference or change their group

i.e.
Avoid accidentally deleting the link to the parent reference
Avoid accidentally deleting the parent reference by changing the group of subreference

User story:
As an editor editing an article in VE
I want the changes I make to parent references or subreference, such as changing its group, to not break the connection between parent and sub - reference
So that I don’t mistakenly break or delete a parent or subreference

Proposed implementation (tbc):
Alternatives to investigate -

1. When the group is changed for a parent or subreference, we could investigate if it's possible to also change the group for all linked references in the family. Show a notice, “you are about to change the group for 5 linked/connected references…”
2. Disable all group editing for parent or sub-references.