I'm new to using ITA Matrix and the power tools, but I'm trying to get an Air Canada itinerary to be a flex fare (as the default seems to be Standard). This is LIH-SFO (UA metal) and the SFO-YYZ (AC metal). I want to book it as an 014 ticket, Flex fare. I've tried F ..-fl as the extension, but that doesn't seem to work when there's a UA flight included. Any suggestions on how to force this?