Hi Steve
Assuming that there is no transport deletion from the STMS queues 
..
You can login to the PROD System ---> go to the Transport Queue ( STMS_IMPORT ) .
In the RC column , search for Transports which are in INIT status ( you can filter this out ) .
The transports which come out are the ones which have been moved into QA ( but not into PROD)
Hope you got my point . In this way , we can filter out the Transports which are needed to be reimported back into QAS post client copy.
Thanks
RD