Could we use User Directories settings for login "User Schema Settings" -> "User Object Filter" with one big group and excent another small group?
Are "User Object Filter" accept "!=" operator for group or another one?
You can use memberOf in the User Object Filter similar to the following (example from here)
An example of != would be something like
More example can be found in https://confluence.atlassian.com/display/DEV/How+to+write+LDAP+search+filters
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG