Your laptop/computer sound card can probably only do 8 speakers max, which will be a limiting factor.
L/C/R Rs/Ls and rear back surrounds.
Dont know if temporarily connecting the height speakers to the surround connections on your amp for measuring would work ?
The other issue could be measuring with the mic in a vertical orientation using a 90deg cal file
So AFAIK at the moment measuring an Atmos setup using REW is not really possible.