Docker: Deploy Workers to Group Other than "default"

In Docker, is there a way to add workers to groups other than “default” upon deployment?

Yes, if you follow the install instructions here:

Inside of the docker-compse.yml you will see the environmental variable for
CRIBL_DIST_MASTER_URL=tcp://servername:4200

You will just want to edit the environmental variable to include the non default group name after the port.
CRIBL_DIST_MASTER_URL=tcp://servername:4200?group=foo

Reference doc for the different environment variable that can be added: