Issue: I want to create a forum for certain members, but I don't want to move them into a different member group.

Method: You will create a new member group in order to to do this, but you do not have to move anyone into it.

Create a new member group for the special forum.
ACP > Users & Groups > Manage User Groups > New Group
Give the new group the permissions for your special forum.

Create (or edit) the special forum:
ACP > Forum Control > New Forum
Set up permissions for just the special member group and the admins.

Check the permissions in:
ACP > Forum Control > Permission Masks > Preview
Edit if necessary.

You can give selected members access to this forum by editing each selected member to override their member group with the permissions for the new group.
ACP > Users & Groups > Find/Edit/Suspend User >
Do not change user's member group. Instead, override member group permissions (tick the box and select new member group from drop-down box)


Their assigned member group will not change, but your selected members will have access to that new forum. No other members on your board ever have to know that there is a special forum or who has access to it unless someone tells them.

That is useful.