We're working on this! We've wanted to explore this for some time; we're tentatively calling this a "super" MR and putting some design time into 11.2 to understand how this might work. Lots to think through here. Love to get your thoughts in the discussion so far: https://gitlab.com/gitlab-org/gitlab-ee/issues/3427
Cool stuff, way more advanced than I thought of. I don't have an account but might create one, on phone right now. But I drop my 2 cents here. I rather see a free version with a simple relationship between MRs.
Basically;
If linked_mr:
print "warning, merging this will also merge:" + linked_mr
...
Function merge()
...
if linked_mr:
merge(linked_mr)
