Reply to Z2/X1/F1 Control FX 3 and 4 on X1 mk2?

Hopefully someone can help me with this.

I have a Z2 and Mk2 X1. I would like to keep control on decks 1 and 2 with the X1 but control FX 3 and 4 with the X1 whilst keeping the Z2 for FX 1 and 2.

What is the best way to go about this?

Thanks

Si