ddj-sz with other cdj (and dvs)

Hi guys!

I can't figure it out if with the ddj-sz i can connect my cdj900 (or my dvs) as 3rd and 4th deck and use it with Serato DJ.

Is possible? Or my 3rd and 4th deck will only work in a standard way as addiction to the sz with Serato? Can i apply sz mixer effects to those decks?

If is possible to use those decks i need to buy other stuff for let them work with the sz?

Thanks guys!