Boundary conditions for a phase in fluent
 

Hi guys,
I am running a VOF simulation with 3 different fluids. What I need is to set 3 different outlet boundary conditions. My problem is that when I try to select the boundary condition type (for a specific phase) only "wall" is available. For me to be able to select outlet I must change the phase to "mixture". Why is this the case? How can I make an outlet boundary condition just for a certain phase and not all?

Best Regards,
AA