I am wondering the same thing. Can Rick pledge them to Gingrich?
where RS has won a pledged delegate, and the delegate already exists, not like MO or ME:
RS has not released his delegates. So he can keep them for the first ballot or release them.
He cannot order them to vote for somebody else. He can suggest it, but not force them. (I doubt he will even be in the convention hall during the roll call ... he has no authority over them.)