Hey Everyone! I'm new to FlyerTalk and I apologize if this isn't the correct thread to post this in but I couldn't find anything else better.

I'm trying to book a one way flight from London to Seattle on July 15th. I noticed that flights were cheaper connecting or originating in Copenhagen so I did a search of Copenhagen to Seattle. Luck would have it, I found a flight on Iberia Airlines from CPH->BCN->LHR->SEA for $755 rather than the typical $989.

I'm in London right now so obviously I don't need to use the previous two legs of the trip. If I purchase the ticket and I don't check in for the previous two legs (CPH-BCN, BCN-LHR) will I be able to use the last leg from LHR to SEA? The last leg of the flight is with Iberia's partner British Airways if that makes any difference.

It's not exactly hidden-city fares which is why I wanted to see if anyone else has done this or knows if it's possible to do this.

Thanks for your help everyone! I greatly appreciate it.