Suppose I decide that I want to start sharing a folder with a colleague and it happens to be part of a backup at present?  Can I just go to the folder on Drive HQ using the Drive HQ web interface or Drive HQ File Manager, make it sharable and then tell my colleague how to find it and access it?  If my colleague adds to or amends files in that folder, will my backup task take care of those changes and make the new files appear on my computer?  In other words, is the backup doing a bi-directional synchronisation by default? If this is not a good way to go about doing the sharing I want, what is a good way? Should I take the folder out of the Drive HQ backup and simply synchronise it as a shared folder?

It is not recommended to share a folder in your backup data folder. If it is shared for read-only, that probably is fine. To share it for read-write access is dangerous.

In your case, please use DriveHQ FileManager, which supports synchronize folders among multiple PCs and multiple user accounts. The 4.0 version FileManager supports scheduled synchronziation, one-way or two-way synchronization.

Thank you for such a prompt and concise reply.  I intend to follow your recommendation to use sync facility  in DHQ FileManager to share project working folders with colleagues.  May I presume that it will do no harm to leave such folders included in the backups which covered them before I decided to share them?  Will it have much impact on my storage capacity if I adopt this approach? 

I have one big project folder containing folders relating to different projects. The big folder is covered by one backup.  Some of the individual project folders will be shared with various colleagues, depending on who is involved from time to time.  I want to avoid having to pay much attention to the backup, letting it just happen while I share and un-share the project folders as required.  If this is going to use much extra storage I may have to re-think.

Please note DriveHQ Online Backup keeps files in \DriveHQData folder.

If you share a folder using FileManager, the folder should not be in \DriveHQData folder. So you need to duplicate your files in another folder. If the shared folder is very large, there will be some storage wasted.

Now if you share the folder read-only, then it is ok to share folders in the DriveHQData folder.