Originally Posted by
TerryK
Many threads about this issue. No, the rest of the itinerary after your skipped segment will be cancelled.
The OP doesn't say anything about intending to skip a segment, and clearly (at least to me) says they are looking at changing it.
The answer is that yes, it should be able to be changed. Though it will cost a change fee (new money) plus any fare difference based on the new routing - if the new fare is less than the old, the fare difference may result in a voucher going to the OP valid for future travel.