VFX graph Particle Strip Capacity question.

How can I control the start and stop of individual strips? I would like to start drawing particles for a single Strip when certain conditions occur and then stop adding particles to that strip when the condition is no longer true. If it becomes true again, I would like to start a new Strip (so that I am not connected to the previous Strip), and so on up to the limit of Strip Capacity. I have the strips drawing as desired, but cannot sort out how to move on from the first strip. Is it even possible to use the StripIndex to move to the next?