You will need to either call or remember to provide your AS number at checkin. I always call right after making the res. so it doesn't slip my mind and you are correct in your statement that DL only allows DL numbers on their website. AS and DL do not share member status because AS is not tied into the SKyTeam system so unfortunately you cannot get priority seating until you checkin and show you AS MVP card and even then some DL agents could care less!