Make them do a "wait" at the top best maybe to start training them one at a time then have all 3 at the top in a "wait" once they have perfected it. Then do a recall once you are at the bottom of the stairs this way you can control them. If that doesn't help then put a lead on them they'll love that LOL! I did the "wait" "recall" with my two :) Good Luck! Hope Star is okay.
Hope Star is doing better now - Ricky tears up and down stairs like a maniac too - sorry no help here! LOL!
We have our stairs blocked so one can go up or down without permission. Not sure if that will work for you.