The bases are loaded and the ball bounces in front of the third baseman. He picks up the ball and touches third for a force-out on the runner coming from second base. Can he throw home for another force out or can the runner who was on third return to third?
This is covered by MLB rule 5.09(b)(6)
Any runner is out when:
(6) He or the next base is tagged before he touches the next base, after he has been forced to advance by reason of the batter becoming a runner. However, if a following runner is put out on a force play, the force is removed and the runner must be tagged to be put out.
Since a following runner is out, the runner from third must be tagged out while not touching a base.