Is there a reason you don’t upgrade to version 2? 🙂
Regarding you question, I just tried this and works:
– Create a prefab BehaviourTree.
– Create a prefab BehaviourTreeOwner gameobject.
– Assign the prefab BT to the prefab BTOwner.
– Add the prefab BTOwner in the scene.
– Hit Apply on the instance.
The reference to the prefab BT graph is not lost.
Can you confirm?