Answer: it does not substitute multiple inheritance.
Example: “InteractiveObject” interface which can be either an Actor, SkeletalMesh, or StaticMesh that the player can click to interact with.
Example: a “SimulationObject” interface which communicates with a separate simulation via a messaging system. It can be a Character, an Actor, or a Components.
In both cases a “class” that parents or extends all 3 not only doesn’t work but also makes zero sense. Advise you to do some interface tutorials because you will use them a lot! 