2 out of 4 row houses

[Collin Cook]

I have been looking for deals in Pittsburgh and think I may have found one. I found a motivated seller with not one, but two row houses in a nice area. However, I come to find out they are part of a quad-plex or 4 unit of row houses. She only owns the two on the right.  They are all vacant and or boarded up, similar conditon.  How much does not being able to control the other two hurt the value of the ones on the right? The other two have two different owners. Two out of four isn't bad right?