"If a friendly character named Storm is on the map, Black Panther and Storm may both use support, but can only use it on each other."

if it's 128 pt black panther, and 46 pt black panther on the map, could they both use support on storm?

Black Panther would refer to the Black Panther that has the power. Since the 46 point PB doesn't have that power, he cannot use Support.