Why does parenting an object to another cause one object to fly away?

I have a cube and it lands in a moving bowl that is moving from side to side. The cube stops bouncing and due to friction moves at the speed of the bowl. But when I parent the cube to the bowl, the cube flies away. Does anyone know why?

Could it be that I need to parent all of the children game objects within the cube game object to the bowl? If so, how to I do that?

Both the cube and the bowl are rigidbodies. The following post has andeeee saying that one rigidbody should not be a child of another rigidbody.

So how does one get two rigidbodies to move in concert? Do I need to use a FixedJoint?