Include parent/super class in a package export?

I have a prefab with a script attached to it, let's call it ClassC.

ClassC extends ClassB, and ClassB extends ClassA - normal inheritance stuff.

Unfortunately when I go to export a package, only ClassC gets included. Unity doesn't go up the hierarchy and include the super scripts. If I drag the ClassA and Class B onto the prefab before exporting, they get added right onto my game object alongside ClassC which can totally screw things up.

Is there any way to make sure necessary scripts get included in a package export so I don't have to manually drag individual script files into a new scene? That gets very tedious.