Using Different Instruments with different hardware

this seems like a basic question, but I caot for the life of me work it out or find a tutorial.

Using studio one v2;

I have an AKAI MPD218 drum pad and an Impact LX49 Midi Keyboard.

I would like to set up a drum track (using studio one's impact drums) and set it so that the MPD218 will always and only play that instrument track, regardless of which track I have selected in the DAW.

the LX49 keyboard would respectively play a seperate track with a piano vst, for example, without interfering with one another.

I'm asking because I have had a few jam sessions and it would be great if everyone could be playing an instrument whilst I was adding and changing separate tracks in the DAW simultaneously.

Thanks guys,

Luke