Upvote:1
It is complicated:
Upvote:3
You will have to call the issuer of the ticket to arrange this. If you don't call first, then missing any flight will normally cause the remainder of the ticket to be cancelled. The airline may charge a change fee, but it's also possible that they'll allow you to retain the return flight without taking the outbound flight.
Regardless, you should call them and explain what you would like to do. Then, if they say that you will have to pay extra to do it, you can weigh that cost against the cost of buying a new ticket.
You may also want to ask whether you can change your outbound flight to one that does not require changing airports. That might be less expensive than buying a new ticket (or it might be more expensive, but you won't know unless you ask).