Thank you for the responses. Although sdsioux's idea briefly gave me hope, I understand and fully support the rule, so will reluctantly shelve the story.
I am looking forward to submitting my first story, but need advice on a major character problem. As written, I believe my story violates the site guidelines and would be rejected. Two of the four main characters are underage. They do not have sexual contact with anyone, but the narrator clearly has fantasies about them; their appearance and clothing are described in detail; and they play a major role in bringing together the two adult characters (the girl's mother and a college-age male). The obvious solution would be to make them older, but I'm not convinced it would be believable. Sixteen- and seventeen-year-old girls would generally have a different level of maturity and emotional motivation than twelve- or fourteen-year-old girls. Also, they would be so close to the age of the narrator as to make the plot unlikely.
Should I scrap the whole concept and start over? Any creative suggestions appreciated!