In that DLC, you the player fight off invaders in return of the deed to the castle. After that, you dump loads of septims to get upgrades and trophies from a taxidermist.
Sounds cool, a tad similar to what we know about Hearthfire...or is it?
http://www.uesp.net/wiki/Oblivion:Unwanted_Tenants Not only that but it was unmarked, so it doesn't appear in the journal.
So the question is: Do you think there is something hidden by Bethesda in Hearthfire? Such as building on top of a sacred site resulting in a chain of events? What do you think?