When calculating odds for set hunting, do you use the Original raisers stack, (assuming you have that much or more.) or do you only use the effective stack?

Example:
UTG-9.00$
MP1-2.00
Hero(BTN)-11.50

Hero Holds 99

UTG Raises .15$ to .20$
MP1 calls .20$
Hero: ???

I use MP1's stack right? and that only give's me 10:1.(I DON'T go by the 10:1 rule BTW.) As a second question, what if it's two big stacks calling + 1 short stack. Do you make the call then?