Adidas had responded on an earlier thread and their response was that is not possible to have more than one plan at a time. Their suggestion was to incorporate some of the workouts from another plan into your schedule. Why don't you check out the running half or marathon plans and find one appropriate for your long runs. Also, I'm pretty sure you can set up two runs for the same day. I've done it before. You can drag the workout from custom workouts onto the day you want to do the extra workout. Hope this helps. It's too bad we can't set up two plans to run simultaneously.
