Normal
You shouldn't need an letter from the judge if you have orders showing that you have sole custody/guardianship, whether you are the parent or a third party. Essentially, a court order IS a letter from the judge. I think in most cases, parents (or others - I work in a family law office and we have one case where the mother and grandmother share custody) either share custody or one person has sole custody and the other interested party has visitation. That is when permission is needed from the other parent, not in cases where one person has sole custody and the other parent/person doesn't have any court ordered parenting time.
You shouldn't need an letter from the judge if you have orders showing that you have sole custody/guardianship, whether you are the parent or a third party. Essentially, a court order IS a letter from the judge.
I think in most cases, parents (or others - I work in a family law office and we have one case where the mother and grandmother share custody) either share custody or one person has sole custody and the other interested party has visitation. That is when permission is needed from the other parent, not in cases where one person has sole custody and the other parent/person doesn't have any court ordered parenting time.