I hope someone can point me in the right direction.

I already have 2 restaurants. I would like to add a 3rd.

I can't remember exactly how to do it.
I know that I have to download the 3rd game to a different device. But I don't want to play it on a different device. I already play the 2 restaurants on the same device by just switching back and forth.

How do I get the 3rd game to be accessible to the device that I already have the 2 restaurants on?!

I hope that this makes sense. Any help will be greatly appreciated.