Hi!

Been earning AS miles for a long time now and decided to pull some redemptions on this fine day. I booked 5x SFO-HND (in J) and then HND-SIN (in coach). It's my first time redeeming miles on AS, It cost 65k per person which I think is a fantastic deal, I'm a tad bummed that the 2nd leg is in coach, but it is what it is. There is a chance that the destination (SIN) might change, is it possible for me to change the itinerary to something like SFO-HND-HKG without cancelling the reservation? If I do need to cancel the reservation, would the SFO-HND in J be available immediately after booking? Thanks!