Training plan calling for a long run, but want to do it with a group run

I have been following the 13.1 training program and its great so far. However, some of the runs are going to be very long. I was wondering if there is an ability to run the distance in a group run, but have it count in your training plan workout?

Also, I dont suppose that there is a way to modify the intensity of the training plan? I ran my warm up faster than prescribed and I didnt get a star for that section.