Actually there's a simpler way, I just forgot 
Don't send anything out from the Collision operator. Then below it, place a Spawn operator and set the mode to 'marked for collision spawn' and then send those spawned particles to another event. Then in the collision operator set 'evaluation timing' to 'in order' and enable 'mark for collision spawn'.
Don't send anything out from the Collision operator. Then below it, place a Spawn operator and set the mode to 'marked for collision spawn' and then send those spawned particles to another event. Then in the collision operator set 'evaluation timing' to 'in order' and enable 'mark for collision spawn'.