In a review of the law applicable to this situation I can find no such requirement.
The same rule applies to a criminal defense attorney in both juvenile and adult plea settings. The attorney's client is the juvenile defendant... not the parents. Therefore it must be left to the juvenile defendant to decide how to proceed in their criminal case.
The attorney's job is to insure the defendant knows of all their rights, the strength of the state's evidence, and the potential sentence they could face if the matter went to trial. They must insure the defendant knows of all the defenses available to them (factual and legal). Further, they must provide whatever pretrial services the defendant requires to prepare their case for trial. This may include factual investigation, legal research, pretrial motions, discovery requests, witness interviews, or any number of things that may be needed to help a defendant make an informed decision on how to proceed. There are no requirements that I've found that a parent be present or informed of a juvenile's plea offer or acceptance. Furthermore, any efforts the courts have made to get parents involved is limited to juvenile court... not criminal court.
However, there is one thing that we should address. A plea of guilty must be knowing and voluntary in order to be valid. If a judge, prosecutor, or defense attorney permits a defendant to enter a guilty plea without assurance that the defendant understands all of the rights I've mentioned and their right to a trial by a jury of their peers, then the plea of guilty could be considered invalid and be set aside. This can be accomplished by filing a petition to set aside a guilty plea as being involuntary (due to mistaken facts, mistaken law, bad advice by counsel, etc).
This is something that should be discussed with local counsel. Obviously we are dealing with an extremely serious issue and it is important to get a second and third opinion.
Please reply if I can help further.