Animation Blueprint Inheritance

I would like all my animatable game characters’ blueprints to inherit from a base blueprint so that I can share the general event handling mechanisms for animation start, end and so on. The alternative appears to be to have to set up the animation system identically for each character. However, when I try to create a “base” animation blueprint it forces me to select a skeletal mesh - which is exactly what I don’t want. It’s an “abstract” blueprint I need. What am I missing?