What is the best way to track defect sources in tfs?

We have various teams for a project like the vulnerability team, the customer, pre-sales, etc. We give a build and these teams independently test it. They do not have access to our tfs system. So they usually send in their defects via email. It will usually be send in an excel format. Our testing team takes these up and logs them into tfs.

Sometimes they modify the original defect description (in excel) and add the expected/actual results. Sometimes they miss to cite the source. I am talking about managing the various sources as such.

Is there a way we can add these sources into tfs, and actually link this particular source with the defects, with individual comments associated with them (saying where in the source we can find the actual material for the defect).