I made a fairly large change in a project, but since it will need extensive QA time leadership asked me to table it and work on other tasks so we can do a quick release without these changes.
If I make a few secondary changes after I create the tableset, then restore that table set, is it going to wipe out the secondary changes?
Or does this depend on a case-by-case basis as interpetted by the TFS merge engine?
I believe you are talking about shelf-sets.
As long as the changes are checked in before un-shelfing, it will not wipe out any new changes made since the shelf-set was made. As you un-shelf, visual studio and TFS will show you when there are conflicts. The conflicts could be easily resolved if different methods are changed or could be hard to resolve if the same lines are changed in both places. The merge tool makes this a little easier.
You wont risk loosing any work because the checked in changes and the shelf-set are always available.
In fact, if you make a lot of shelf-sets you may find yourself cleaning them up when you have too many to sift through.