Cast to Child actor


So I have this blueprint setup:

-----------------------Base Character
-----------NPC Base ---------------Player Equipments
-----------… -------

I am trying to set up the experience system, but I have an issue.
The Base Character (parent) contains the Take Any Damage, hence I must give the experience from this blueprint. However… I need tell the game if the player receiving the exp is either NPC or Player, so I must “down cast” to check if its valid… so basically if I downcast to NPC and is not valid, then Player will be valid and give the experience.

So my question is… How can I downcast correctly from a parent blueprint to a child?