I am realy looking into this feature, but there are just some things and make it very difficult to implement properly and without unhappy accidents.
Currently the way to parametrize subtrees would be using Blackboard variables.
Since blackboards live in the GraphOwner game object and thus in the scene (in case they are not prefabs anyways), they can have scene object references.
Nodes can then use those variables instead of direct drag&drop references 🙂
Gavalakis
