In order to go from one TA to another you do have to cancel your original ressie. It's kind of frowned upon to do that, but it is your perogative as the customer. However, if you rebooked onboard and then transfered your ressie keep it that way, otherwise you will lose your rebooking credit, I believe. Once a reservation is booked with
DCL and transferred to a TA, that TA has control over the ressie. There's technically no transferring the ressie back solely to DCL then retransferring to another TA unless the original TA has done a horrible job as your TA. I could be wrong but I think this is what I read. Plerase do still ask because I am usually wrong 99.9% of the time on things!!