RBK12 Router as satellite?

Hi all,

I have a RBK13 system running, the small cubes. One router, one satellite. Now, I need to extend that to cover my home and my garage completely. Single RBS satellites are unfortunately not yet available in Germany, but RBK12 kits are (one router, one satellite). What if I buy one of those to add

- the satellite to my existing network? Should work as satellite 3, or?

- the router to my existing network as just a satellite 4 w/o router functions? Does that work?

Anybody tried that already?

Thanks and cheers, 

Sven