How can I parent a GameObject to and instance of another GameObject?

I have a game object sitting in the level I am currently creating and when the player gets near it I instantiate a prefab at the same location. I want to have the original GameObject attach to the instance so I do this:

orginalGameObject.Transform.Parent = instantiatedGameObject.Transform

but I get an error telling me that parenting to an instance is not allowed to prevent data corruption.

Is there a way I can do this? I want the original GameObject to be attached to that it can be dragged away by it. The instantiated GameObject is also a RigidBody which is jointed using a spring joint, just in case this should make any difference.

Thanks for the help.

OK, so when I went back to this bit of code I found that I was not referencing the instance of the prefab but the prefab itself so a change in the code to instantiate the object to a GameObject allowed me to reference the instance and parent the original game object to this instance.

InstanceGameObject = Instantiate (Prefab, Vector3Position, Quaternion.identity) as GameObject;

SceneGameObject.transform.parent = InstanceGameObject.transform;

Works without error.