Scarf was/is in a polyamorous relationship with 8 to 10 people. I don't know the exact number. She cheated by not informing all her partners. In polyamory you need to inform all potential future partners that you are poly so they can decide if they feel comfortable dating a polyamorous person. The failure to do so goes against informed consent.
Another important thing to remember is polyamory is ethical nonmonogamy. A polyamorous person should only date as many partners as they have time for. I am polyamorous and my personal limit is dating no more than 4 partners at a time. Other people’s limits will vary.