Pupil trapped between warring parents
A I have said many times that schools should avoid getting involved in matrimonial disputes. Rather than take sides in this matter, you should refer it back to the parents to make their minds up. If need be, the mother will have to seek a custody order through the courts or, at very least, seek a ruling on the question at issue. Until they have sorted themselves out, the school should not agree to include the pupil in the party.