@Jon Holdman, Thank you for your reply! Everything about the purchase was legitimate, we used attorneys and a notary provided by the mortgage company. We have a mortgage, didn't pay cash. Essentially it was a "normal" purchase (just so happens it was his parents), we had a CO inspection and appraisal, we just didn't use a realtor. We also have audio recording from before the purchase and text messages in which his parents say, "We can no longer afford this house" and "We want you to buy the house".
As for the belongings, we don't want them. However, as I mentioned they are somewhat of hoarders and we know for a fact a lot of things will be left behind. From what I've gathered, we are able to put the things outside, but as I mentioned they have A LOT of things. How long do we have to leave it outside before we can get a dumpster and throw they're things away?
This is just such a crazy mess and we are asking our attorney as many questions as we can think of but I figured I would ask people who have been through similar situations. I agree that we should look at them as occupants, not family. Believe me, after this crazy situation I don't know what "family" relationship will be left. From what they've been threatening us, they seem to think they can try to incriminate my fiancé with "theft by deception". But from what I have read about that, my fiancés case doesn't fall into those parameters.