The father of a first-form girl left in educational limbo today launched a High Court challenge over being denied a place at an east Belfast high school now attended by her sister.
A judge was told the refusal, based on criteria of having siblings as past or present pupils, was unfair.
Judicial review proceedings were brought against an admissions tribunal decision on the 11-year-old's application for Ashfield Girls' High School.
Her family, who cannot be identified, want her to be educated there along with an older sister to now attends after moving from another school.
Their position is intensified by medical issues involving one of them.
But although it was confirmed in April that the older girl would be starting Ashfield this term, her younger sister was refused a first-form place.
Admissions criteria includes giving preference to those with a sister who currently attend or did so in the past.
Counsel for the family, Sean Mullan, claimed it was unfair of the board of governors and the appeals tribunal to "ignore" the unusual circumstances of having older sister about to transfer to the school.
The court heard that the younger girl is currently without a school, with no others having been nominated in the post-primary process.
Paul McLaughlin, responding for the education board appeal's tribunal, acknowledged the refusal decision came after confirmation the older sister was to move to Ashfield.
He expressed "enormous sympathy" for the girl, whose representations to an exceptional circumstances body also proved unsuccessful.
But he contended: "The criteria is not ambiguous, it's quite express in its terms.
"The applicant did not satisfy it because it requires they had a sibling who attends or attended."
During the hearing Mr Justice Treacy said it seemed "exceptionally technical".
Ajourning the case until Monday, however, the judge asked for more information on the exceptional circumstances application.
Outside the court the girl's father stressed his desire to have his daughters to be able to go to school together.
He added: "It's ridiculous, they knew my older girl was going to be a pupil at Ashfield. We have been treated unfairly."