You can actually type in a sort of formula in the watchlist to monitor the price of an option spread. In this screen shot see where I put in the formula for a vertical put spread. Sold a 6/28 52 put and bought a 6/28 50 put.
So I just subtract the value of the 50 put from the 52 put. Then once this is in your watchlist you can associate it to show up in all other views.