Do you have them labeled? If so, and if you're hesitant to cut and remove all the growth above the cut, don't worry. Just cut the 3's back and do not remove the foliage that's dead. New growth really will cover it. Then you can decide if you want to move the group 2 clem after they've all bloomed.
Yes, I do know how ugly this looks but it gives you the idea. First I cut it back (to be sure the job was done) and when I had spare time I did remove the top but if yours are mingled together you'd risk reduced blooms on your group 2 clematis if you cut all the clems in the area to the same height.
