Companion fare multi-city question: We have two separate trips upcoming, one late summer and one early in the new year. Our home base is PDX, and it would consist of something like DFW-PDX (one way in August, using AA for the route to Dallas), and then months later is PDX-OGG-PDX (roundtrip in Feb). Using the Multi-city search with the companion fare applied, it actually will let me get to the checkout screen for this itinerary, so seems like it would book out, and I can get the benefit of at least one more leg (DFW-PDX) being on the companion fare as well.

Big question though, is there a major risk or downside to this? What happens if we fly the first trip (DFW-PDX), but travel dates need to change for the later trip -- can we? The several months difference gives me pause, but the $400 savings is extremely tempting..