Reply to Running S4/Scratch Pro/Serato SL2 together

This might be a silly question or one that's been asked before (if so, please redirect me, don't want to waste anyone's time).

I was wondering if it's possible to run SL2 and Traktor at the same time from 2 decks and the S4. I run Traktor Scratch Pro with two 1210 going into an S4 with the timecode update. But my friend uses Serato. We are doing a back to back gig and I wondered if there is a way of setting up so we can both work seamlessly.

My first (and probably wrong) thought was to run the vinyls into the SL2 and out into the inputs of the S4 (3&4). He runs his laptop with the USB connected to the SL2 box. I run my laptop with the USB connected to the S4. Main comes out the S4 and into the sound system.

Will this work? Or will either the signal from the SL2 or S4 interfere? Or is the S4 simply not compatible to do this?

Thanks