Juvenile justice sucks. And I say that as someone who has spent most of the past 20 years working in the juvenile justice system. I could go on and on, but I'll say this...I've worked in all aspects of the court system, and there's no place I'd rather work. It's the one place in the system where you actually can make a difference in what you do. Treat a juvenile the right way, and that kid may never commit an offense again. Give them a hand up at the right time, and you may help her turn her life around. It's the one place in the system where there is still some hope.
As to the OP, the law (at least in Ohio) requires that the court consider the age, intellect, and experience of a juvenile before admitting any statement/confession. I personally have thrown out a few confessions because the circumstances led me to conclude that the juvenile's constitutional rights were violated. Sometimes by an overly aggressive officer (or officers), sometimes simply because the juvenile's own limitations made what would normally have been a good questioning unconstitutional.
And, about the parent issue...in my opinion the parent issue is a landmine. I've seen parents go into an interview room and become the "bad cop" in the situation forcing a confession. Seen parents overrule the juvenile's request for an attorney. heck, I've pissed off more than a few parents in court when they come in and say things like"he's admitting to this because I don't want to take any more vacation time coming back here," and then I don't accept the guilty plea and order an attorney and guardian ad litem appointed.
Yep, it's just juvenile court after all. Gotta love it.