Pull the queens a little closer together to reduce the bending stress on the tie beam. But keep the queens near the ends of the collar, so raise the collar as well. And like Mike says, if you use material that shrinks a lot, the queens stacked on the tie beam is not the best idea. If you're using white pine or relcaimed material, it should be OK.
PS: You may find this page to be of interest:
http://www.northernlightstimberframing.com/su/
