Hi Indengr
I think you have stated the solution you want not the problem you have.
You really are after data sets (Ibays, folders whatever) that some people can get to and others can not. Ibays provide exactly this, through the use of GROUP access.
In your example you use A-1 for Admins, A-2 for admins and drafting - easily done:
Create two groups ("administrators" and "drafting").
Create two Ibays ("adminstuff" and "draftingstuff").
Put the users who you want to be admins into the "administrators" group, and both admins AND drafters into the "drafting" group.
Grant R/W access to "adminstuff" to the group "administrators"
Grant R/W access to "draftingstuff" to drafters.
In the above example "admins" are people you want to be administrators (DO NOT CONFUSE THEM WITH THE admin USER BUILT INTO SME) and "drafters" are the people you want to be in the drafting group. I have used "adminstuff" instead of A-1 and "draftingstuff" instead of A-2. Change these to whatever suits you.
You can, of course, extend this model indefinitely by creating other Ibays and groups. Just make admins part of any other group you create so they can have access to the new Ibays.
Now for the backup:
The normal backup-to-desktop picks up your system settings AND Ibays....but is limited to 2Gb. This backs up from the SME server to a workstation you are using.
DAR2 and others are backup contribs that also backup system settings and Ibays. You need one of these if you have more than 2Gb of total data.
Affa contrib is an SME server especially configured as a backup server with the added bonus that it can be "promoted" very quickly to take the place of your main SME server in the event of a hardware failure.
That should, I hope, cover the problem as you outlined it.
Many times in this forum we are advised to "Read the manual three times to fully understand it". And get to know what contribs (addons) you might need.
Good luck
Ian