my concept is that the old Furby generation are the ancestors of the current Furby.
Explain:
There is an ancient settlement of wild Furby (aborigines), they are very large and unfriendly but once when there was a severe cold and a whole group of wild Furby began to migrate to a new place of residence. Alas but from them lagged baby Furby which then found and domesticated people. AND SO BEGAN THE SELECTION OF FURBY. From generation to generation the people had multiplied and taken out of a new breed of Furby (found orphans or steal the eggs right from under mothers).
Here is so and appeared current Furby! Small fluffy friendly lumps of happiness whose ancestors were and are giant sullen creatures

Sorry for my EngLiSh