Feature:90097 Unmerge Facility
I think the title/pub level feature we're looking for is really: "Remove a pub from this title".
From a title displaying pubs, choose "Remove a pub from this title". It redisplays the same list of pubs that were there before, including any that are listed as variant children. A radio button is next to each title. Pick one and choose "Remove from title". This submits a request for remove. If the selected pub pointed directly at the title that was being displayed, this will create a new title record, identical to the current title record in every way, including any pointers to a vt parent. It will then change pub content so that the selected pub points to the new title record instead of the one that was being displayed.
If the selected pub was a vt child, then the new title created is a copy of the title that pub pointed to, again including the variant pointer. Pub contents are changed as above.