Sources are various fan reports from twitter and Kunieda5gogo’s blog: a very dedicated and cool jp fan going to as many Pretty Rhythm events and talk shows as possible and writing down what was said. I already linked it in the past.
On October 9, 2016, there was an event to celebrate the release of the first Pretty Rhythm Rainbow Live BD box. IIRC tickets for the events were in the preordered copies of the 1st bdbox. People present were Avex Producer Nishi Hiroko who was asking the questions, Katou Emiri/Naru, Serizawa Yuu/Ann, Komatsu Mikako/Ito and Sakura Ayane/Rinne.
Needless to say, this contains spoilers.