Please note when multiple people edit the same document at the same time, only the last one will be saved, resulting some changes be lost. DriveHQ does NOT lock the file when a file is being edited by a user. To enable multiple people to edit the same file, you need to share a folder to multiple users with Full-Access right. All users must be DriveHQ member. It is much easier and more convenient if you have a group account as the group owner/admin can easily create/manager multiple sub-user accounts.
Note it is problematic to lock a file on the Internet as there is no way the web server can detect if the user is still editing the file or not. If we lock the file, and if the user's OS or browser crashes, or network disconnects , or user accidentally closes the browser, or he just forgot to unlock the file, then nobody else can edit the file; in some cases, the user himself cannot edit the file.
To work around, when multiple users are editing the same file, each user can change the file name, (e.g. change project.doc to project_john_08192007.doc) before he starts editing, this is equivalent to "lock" a file, but other users can still edit it if they want to.