Does the hand actually call the OnTriggerEnter/Stay/Exit functions?
Mine doesn't and that's a major problem.
And to solve your problem:
In Unity a Gameobject can only have 1 collider. If you want multiple collider do this:
- Create an empty gameobject
- make it a child of your gameobject
- give it your wished collider as a component
You can give a gameobject as many children with collider as you want. When you did this, it would be nice if you could come back and tell me whether it's working and especially whether your trigger is working and registers the Hand.
Also I hope you are using the Interaction Engine Brush Hand that you should use with the Interaction Engine.