I'll check on that misprint! You're right that the misprint does not affect game play.
If there is a Ground Out result where only the runner on 3rd gets to advance, shall we assume it is a force out at 3rd if there were runners on 1st and 2nd?
Yes. I envision an attempted double-play where the lead runner is out and the hitter is safe at first.
Similarly, a ground out with no advance is a force out of the forwardmost forced runner. Correct?
Yes, again, I envision an attempted double-play where the hitter is safe at first. With the bases loaded, the force out would be at home.
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