Which full function are you looking for?
With the SC5000 now being an “authorized accessory” for Serato, you could probably have your cake and eat it to. Set up the 6000 MKII as primary controller, then add the SC5000(s). Routing the audio might require some study, but technically I think it should work.
I think I read somewhere on these forums that there is no sound routed back through the SC5000, so you’d need to be able to tell Serato which controller controls which deck. But I do believe that is doable.
Using the SC5000s as regular stand-alone players attached to the line inputs on the MC6000 is of course always possible. In which case you could still use two channels on Serato and use the SC5000s with Engine Prime USB sticks.