Yes exactly, only include the Game.qml once for example in the Level, or wherever your entityContainer is pointing to. All your children elments can then access the game component with the id. Consider this example:
// all entities can access the functions and properties in Game.qml now with gameLogic.
//.. put the scenes and the EntityManager here
Also see the Chicken Outbreak or Squaby example, which allow accessing the player instance from all entities similar to this approach.