There’s currently no option to merge/consolidate editions as a single library item. That being said, there’s a feature suggestion to address this for which you can vote.
Personally I’ve created an „alternative cuts“ collection and added all „non primary“ movie editions to that as a workaround. The collection is configured to hide its items, so only the main editions are listed. I can access all alternative editions through that collection or from the „Other editions of…“ hub of the primary edition.
