Can I make a pre-existing Class Blueprint the child of another Class Blueprint?

I’ve got two NPCs in my game, and each of them naturally has a separate class blueprint. Now I want to create a parent class and make these two NPCs the children of that parent. Is there a way I can do that, because the only way I’ve learnt to implement a parent-child relationship is to create a child class from the parent itself.

Yes, you can do that by first opening the relevant blueprints, then click on File >> Reparent Blueprint. It can create some compile errors if it finds variables with similar names in both parent and child. You’d have to rename or remove these as required. In any case, I’d suggest creating a backup copy of your project before reparenting your blueprints.

You can always re-parent (File->Reparent Blueprint) a Blueprint but if the existing Blueprint is overriding some functions that doesn’t exist in the new parent they will obviously break.