French site Fraizesauxsims3 (that’s a mouthful to say) has a three page report on The Sims 3 Generations.  They share with us videos (which I think wont work in Google Translator as well as many new screens!

The imaginary friend is like a doll at first, then it will become an articulated doll with whom you can do the same things with other sims, but only the owner can see it! The imaginary friend with him grows, it will reflect your sims as we said Graham, referring to the Angel who had the same morphology as the sims.

If you want your friend to become real, you need to create a potion to transform an opportunity or when you propose a moment of the game on two different PC, the imaginary friend had the same name by becoming real: Hunnydoll! ! But nothing prevents you from changing its name to the town hall! Hunnydoll install in your family but have no kinship with it.

plenty more of that here