Restrict user to access only one topic

Yes, that’s probably what I will have to do. I understand it’s a very unique access. I basically run a private chat for 100 of my clients who all want to communicate with each other. In addition, I want to be able to offer third party “vendors” to have a “store front” or contact portal where my members can ask questions that others can see and find updates on what the vendor is up to. However, I don’t want the vendors to see any of the threads my general members have access to, nor do I want the individual vendor to see what other vendors are posting or communicate with them. Ideally, I would also want to limit the vendors from seeing the profiles of anyone else although I’m not sure if this is an option at the moment. I won’t have that many vendors, so I can do the manual group setup per category (although I understand that I would still have to have vendors stay on level 0 (locked) and keep all members on level 1 at a minimum, so that the general forum requires minimum level 1 trust level to access and all the vendor threads are accessible by level 0 also but only for each individual group with each individual group containing one vendor and all the members.