Probably nothing to do with the codeshare ticket thing but AY seat reservation IT is totally appalling. I have a J award, on which the outbound was cancelled and I was moved to TG J (much appreciated) and then the inbound I moved ahead by few months. All these 4 dates/flights are visible when pulling the reservation and it ”insists” that ”there’s been a schedule change”..for the already flown outbound…but all the online functions, seats/food/luggage etc. are gone…really annoying..booked the missus on the same flight but cannot change my seat without bothering AY, so unefficient and also embarrasing to bother the WA team with a seat change that should be a click on the App/Web kinda thing..