What about from a line facing out with the girls in the center, then have one of the girls turn around - a 3 and 1 line. My question is: Who does the U-Turn back? The girls, or one girl and one boy? In other words, do you think you reevaluate who the centers are for the U-Turn Back?
Centers Arm Turn 1/4 and U-Turn Back toward each other as Ends move up 1/4 as in Fan The Top (Isolate).
Usually ends in a Line or Diamond.
Note: I believe that the Centers Arm Turn 1/4 instead of a Hinge. I'd be annoyed if the caller had them facing the same direction (i.e., a Couple) and called Zip The Top. On the other hand, if the caller had the Centers facing prior to the call (e.g., from a Diamond after the Centers 1/4 In), I'd think it would be fine.
Of course, Zip the Top also lends itself to the standard abuse of turning it into an 8-dancer call (e.g., it can be called from Out-Facing Lines after the Centers do a Mini-Chase).
As for who does the U-Turn Back, in my opinion, there is no re-evaluation. Centers Arm Turn 1/4 then U-Turn Back, and the Ends do their part (Isolate).
