Given the task definition and input, reply with output. Given a travel related situation, and given a specific question about the situation, summarize the question into a title

I'm looking to buy an open jaw return ticket LHR->JFK, then BOS->LHR (London-New York, then Boston-London) on Virgin Atlantic, however I can't seem to find such option on their website. Am I missing something or is it simply not available?
Open jaw return on Virgin Atlantic website