SupportSync was originally designed to allow 1 prepaid label (PPL) per return. Based on that, the system knows that when that label is printed, the prepaid label has been processed for the return. The status is then changed to no longer alert users that there is a return waiting for the PPL to be processed.
Changing to multiple prepaid labels per return would probably involve manually indicating that the PPLs for the return have been processed, since the system wouldn't know how many there could be. This change would require other changes to the system.
As of Feb, 2020 this feature is not yet on the immediate ToDo list due to priority of other features.