To maintain consistent group permissions in diretcories, set the group set-uid bit on a directory. For example if you have a directory such as:
drwxrwxr-x ken admins test1
And you execute the command: # chmod g+s test1
Then the directory will look like:
drwxrwsr-x ken admins test1
And all files created in the directory will have a group of admins.