Transferring NLA strips between Blender files

I have a series of about 40 characters(as seperate blend files) all with the same skeleton and animations, setup to be rendered for an isometric game. These animations are arranged in the NLA editor, duplicated for each camera angle and I have tracks underneath that turn the visibility on and off for the various weapons that need to be rendered.

I now need to add in additional animations to all the characters, which involve some of the weapons. The only way I can think to do it is to make the animations, import the actions into each file and duplicate all the strips for the animation and the weapon visibility. This would be fine but I don’t won’t to do it 40 times, is there are way to transfer all the NLA strips between files?