Currently, there isn't any way of detecting other constraints/components in the constructions of fusibles. A solution to this would solve a number of other issues.
Potential solutions:
Save pointers to constraints under a GUID in the game state, and save the same GUID to the constraints. Constrained components would be searchable using the constraint pointers, but this could be over-engineered.
When constraining components, destroy the initial component and add it to an actor. If there isn't a constrained actor, one can be spawned in. It would be easy to detect what construction an object is a part of with GetOwner(). This would require a pretty significant rework but would be cleaner, and make it very easy to set up activations and interactions, but it would make setting up activatable objects a little more painful as they would be better off as components, not actors.
Currently, there isn't any way of detecting other constraints/components in the constructions of fusibles. A solution to this would solve a number of other issues. Potential solutions: