Call Parent Pop-Up Jquery function from A child Pop-Up?

Question

I have a scenario: (A) Parent Page => (B) Child Pop-up => (C)Child Pop-Up.

I am using window.parent.FunctionName(); for calling jquery's function from B to A, It's working fine.

But I am unable to call a function from C which is defined on B. I am using bpopup with MVC 3.