"Living" at a place while For Sale (Deep Discount)

[SMiLEsCRiES]

I'm looking for info about people living in a house/condo while it's for sale by the owner at the same time.

Basically your living at the place for a steep discount, but you would have to move out at any time if it sells. I heard a reason they do this is because places on average sell more often when there's people living in them, as opposed to vacant.

I just briefly heard about something that works like this years ago, but have not found any info while searching now. Is there even a name for this?

Any info is greatly appreciated.

thank you