RebeccaRabe1362003 & KarenChaney1356543,
Spurred by the "No one else has this question", I have to say that we DID have this question, back before we got all our working practices in place, working around the lack.
I believe Test Sets are a close cousin of User Stories, and yet where User Stories can contain other User Stories, there currently isn't any way to make them contain or be associated with Test Sets. But it might not be too technically demanding to achieve that?
We have to be careful about a Work Item that has been Accepted showing up later with fails against it. But if you have a more sophisticated understanding of the serial re-use of the Test Set (and can express that to your auditors and any stakeholders with access to the system but only partial understanding of what everything means) it should be something you can work with just fine.
It may be too late for my organisation without implementing a major project, but if you 'ideas' it, I'll vote for it on principle!