Not quite sure what you mean here. You lost the
staff group declaration in
mress:10003 Z$ dscl . cat /Groups/staff
mress:10004 Z$ grep '^staff' /etc/group
The file definition is only used before Directory Services is started during boot — and I suspect not even then.
If you mean the folders are no longer in group
chown staff to fix them. Alternately, use
/Applications/Utility/Disk Utility.app, select your boot drive from the sidebar, and click "Repair Disk Permissions".