Dance Diva Web-Based Formation Creator Tool
Also the NEW SmartDancer tool is now available (March 2018) that allow you to more easily create formations IN-WORLD with tall 3-dimensional Bot-Positioners. This new system makes use of a SmartDancer Controller and Palettes (with the addition of the SmartDancer script and nc).
You do not need to provide Follower-Relays to the group of dancers. What you give up is the ability for dancers to temporarily do mid-routine solos.