Give other users right on directory. Files created by root are editable by group users.

Link

http://www.udel.edu/topics/os/unix/general/groupsharing.html




Now this directory is correct for group sharing, but new files will not be correct. New files will be owned but the group of the shell and will not have the correct permissions. If you start the shell in the correct group and set the umask command you can make new files automatically owned and permitted properly. However if your group members put file here with ftp or scp, these shell commands will not help.
Instead we will use two commands to solve this problem. The command:

chmod g+s groupshare

will set the "set groupid" bit for the groupshare directory. This means all new files will be owned by the group of the parent directory instead of the current shell. In this case, group which is 0217 will be assigned to all new files or directories. Also this "set groupid" bit will be set on all new directories, so the group will be properly set for all files in the hierarchy.
The command

setfacl -m d:u::rwx,d:g::rwx,d:m:rwx,d:o:r-x groupshare

will set the default:user, default:group, default:mask and default:other. These defaults will be used to set the permission modes for any new file. You must set all these defaults, so this means you have a long command. That is why we used the abbreviations d:u,d:g, d:m and d:o.