How do I send midi information back to my controller with MainStage?

I want MainStage to send midi information back to my midi controller. I use a simple midi drumpad to control MainStage buttons live. I use one drumpad (midi note A2) as the play button, and it's mapped to a play button in my MainStage layout. I know the drumpad lights up when midi note A2 is send towards it. My question is, how do I make MainStage send out the A2 note as long as the play button is active? This would be super nice live, because I will be able to see the status of my play button just by looking at it on my controller.

Any help would be appreciated!