If you want to know if a given pilot effect can modify Snap Shot, "pretend" that the pilot-effect is played by X, and the Snap Shot pilot is played by Y. Then ask yourself, "Does Y need to ask X to modify Y's Snap Shot, or can Y just do it?"

If Y needs to ask, the Snap Shot can be modified.

If Y can just do it without asking, the Snap Shot cannot be modified.

This is a simple conceptual framework for determining what the source of the modification is. I haven't found a modifying effect for which it produces an incorrect answer.