DDJ 100 Recording and adding synth/drum machines

HI, 

I have a DDJ 1000, I'm using my audio interface as the sound card. 

I play other synths and drum machines via the interface when I'm playing my sets. 

I want to record the synth/drum machine together with the output from rekordbox to have a consolidated/hybrid set recording. 

I'm not sure if I can do this or is the only way to do it would be to add the synth and drum machine to a channel in the mixer. 

Appreciate help.  thanks,