Communication with the Microsoft TFS server is very strict and places certain restrictions on how your Help+Manual projects can be stored, updated and synchronized. Please read the points below carefully before starting work. This will help you to have a trouble-free experience when editing and updating projects connected to a TFS server.
Microsoft Team Foundation Server is entirely server-based. There is no "client application" on your local computer as there is with SubVersion. To integrate with TFS, Help+Manual must communicate directly with the TFS server to create projects, download local working copies and synchronize the changes you make in your local working copy with the master version maintained on the TFS server.
As you may be aware, MS Word's new DOCX format is really a container for a collection of files, but when you edit it in Word it is still treated like a single word processing file. You need to think of Help+Manual projects linked to TFS in the same way. Each project consists of many individual files, but it is always linked to the TFS server as a complete unit.
This means that when you open your local working copy of a Help+Manual project that is linked to TFS, you are always opening the entire project, just as you open all the internal components of a DOCX file when you edit it in Word. When you synchronize your working copy, all the current changes in the working copy are uploaded and merged with the server version, and any new material on the TFS server is simultaneously downloaded and merged with your working copy.
You can't just check out individual topics and work on them on their own. You edit individual topics, of course, but always as part of the entire project. And to commit the changes in a topic you must always synchronize the entire project via your working copy.