In sequence diagrams, you can add and remove lifelines that are covered by an interaction fragment, which includes combined fragments and interaction occurrences. When you remove a covered lifeline in a combined fragment, all messages and interaction fragments that were contained in the combined fragment and were covered by the lifeline are also deleted.
Parent topic: Creating combined fragments in sequence diagrams
Parent topic: Referencing interactions from within other interactions
Related concepts
Interaction occurrences
Combined fragments