How to share particular file of Mapped google drive to user
1. Create one more user in Owncloud.
2. Go to the external storage of first Owncloud user.
3. There is setting option at the end of mapped google drive , click on setting, select enable sharing. Also enter created another user name.
4. Now Google drive will disappear from first Owncloud user application, it will present in another Owncloud user account.
5. Now second user can share particular file to first Owncloud user.