Are those who are accompanying or following others (e.g. a soldier with his commander
or a servant with his/her sponsor/boss) and are fully unaware of the destination permitted
to take advantage of the license to shorten the prayers?

If the people in question know beforehand that those whom they are following had the intention to
travel, then they would be permitted to shorten. On the other hand, if they were fully unaware of the
intentions of those whom they were following, they would be allowed to shorten prayers once they
themselves set-off with the intention to travel apart from their companions. This ruling is the Hanbali
and Hanafi opinion.