Controlling which group id is granted access to new files

[Ed J]

Is there a way to specify which group id is to be granted access to newly
created files in CVS?

We use CVS access via SSH (actually :ext:) with unique usernames for each
CVS user to interact with the repository.  We assign a unique group id to
each CVS module, then selectively grant group membership to individual
users.  Even though I've run chgrp on an entire CVS module to set its group,
when a user creates new content in that module, CVS assigns group access to
"users", giving anyone with shell access visibility to the file.  How do I
get CVS to use another group id?

Thanks,
Ed