For a 1-to-1 relationship like this, you do not need an interface. Providing all parties are in the scene:
- dome actor:
- the aButton actor has a variable of type aDome, Instance Editable; calls a custom event above when hit:
- 3 unrelated actors: the player + button (cube) + dome (sphere)
The arrows show how you can choose an actor the button will talk to.