This is irrelevant. A 13 year old cannot consent.
In that case, neither can the 12-year old boy. So charge'em all, and let God sort it out.
"This is irrelevant. A 13 year old cannot consent."
If 17 was the oldest, its seems that all of those involved were minors and therefore couldn't consent. So are you going to charge them all for raping each other? No, you get this girl some help, and figure out who molested her as a child to set her up to make herself such a victim.