Josef,
Thank you. that did indeed give me another perspective. Not one I like very much though!
It doesn't make sense that a Flight (ETE journey with multiple segments) coudl have non-contiguous segments (single A to B plane jounrney).
And the alternative i.e. to manage the issue of connecting up the segments (i.e. where Flight A->B->C->D and B->C is deleted) just adds unnecessary complexity.
I do not like the solution I am proposing: If user deletes Segment (ETE journey with multiple flights) then they effectively search again but with the remaining segment selected. But it strikes me as the most intuitive to the user and also the easiest to design for.
Still not very happy about this one though...