After my experience transiting BA --> AS at SEA a few weeks ago, I'd say don't bother with the interline and just exit, take the train to the main area and check your bag again there. The AS transfer desk was staffed with only 1 person, and there were at least 30 people in line trying to get their bag re-checked. Once you did that, there were probably at least another 100 people in the 1 open security line. It may have just been bad timing, but there were 3 DL international flights, a Hainan flight and a BA flight that all landed within 20 minutes of each other causing chaos. I just gave up and exited and went to the AS check-in desk in the main terminal. I probably would have missed my flight had I not done that.