Trying to embed Group in wsasme.msi using Orca

I need to embed a group association into the wsasme.msi file before providing the installer to a client.
 
I've reviewed the documentation and tried to use Orca.exe to do so, and in my tests the endpoint is always added to the Default Group.
 
I've selected the group I want to specify, then from the Actions menu chose 'Deploy endpoints to this group' in order to obtain the group code. 
 
I then tried setting the CMDLINE property in the .msi file to this:
"SME,quiet,Group=-nnnnnnnnnnnnnnnnnnn" /qn /l*v %windir%wsa_install_log.txt
 
Trying to make this work, I've tried making the word group lower-case.
I've tried removing everything after the quote marks (at the end of the Group code).
I've tried using the Group name instead of number.
 
No matter what I try, my test endpoint is always added to the Default Group.
 
My test endpoint is a VM, and after each failed attempt, I am uninstalling WR, deactivating the endpoint in the WR portal, renaming the endpoint, and changing its MAC address, before I re-attempt the install.
 
How can I get the endpoints to go to the targetted group in the portal?
 
Thanks.