Can I track two runs simultaneously?

Can I track two runs simultaneously? I would like to run e.g. 15k. 5k in a moderate pace, 5k fast, and then 5k moderate again. Is it possible to start an activity, then after 5k start a new activity, when i’m increasing my pace (without stopping the first activity), then after 5k stop the second activity and then return to the frist activity? Basicly i would like to know my total time of the 15k as well as the time of my 5k, without having to split the activity in three. Any help is appreciated, thanks.