Asigning Phases to Regions for Eularian Multiphase
 

I am currently working on Star CCM+, I am using Eularian Multiphase but I am unable to assign the two phases to specific regions, the regions box is a faint grey and can not be changed. My model is of a small tube inside a bigger tube and I want to have one phase acting in the larger tube and the other in the smaller. Is this possible with multiphase and VOF method?
Any help would be greatly appreciated

for each Region, under Physics Conditions, Initial Conditions Option, select Specify Region Values.
This overrides the global initial conditions for this region, then set the required phase ratios. Do same for the other region.