This is exactly the problem interfaces solve.
Inheritance is, generally, a bad design pattern. I know that Unreal has jammed its actor system into the implementation inheritance jar, but that doesn’t make it actually good.
You can add two functions to your interface:
- GetMyValue() → Value
- SetMyValue(Value)
Once you do this, you can just pass the interface around, instead of having to pass a class instance around. Whenever you need to read the value, call GetMyValue(). Whenever you need to write the value, call SetMyValue().
This is literally the problem interfaces are designed to solve, as @Everynone is saying.
Separately: if you re-parent your Character to just be an Actor, then it’s no longer a Pawn, and you can no longer make it a player character, make controllers possess it, and so on.
(This is another problem with inheritance – it would be better to make “can be possessed” be an interface, or maybe be implemented by having a component instead. But that ship sailed long ago 
)