Possible to name movieclip that's at a set of coordinates?

Gidday

Given a set of coordinates, and the name of a parent movieclip within another movieclip of the same same, is it possible to

a) test to see which (if any) parent's child clips is on those coordinates?

and

b) if so, get the name of that child clip?

Or is it a matter of iterating through ALL the display elements of the parent and doing hitTestPoint checks?

I ask as I'm trying to figure out a way to allow buttons within a movieclip within a Greensock blitmask to be clicked, based on how far the finger drag was ie less than 20px, count this as a click, not drag, so get name of child of parent in Blitmask that is on those mouse coordinates.

Cheers guys