A supplementary guardian is appointed by the court if the child is under parental care or guardianship but the parents or guardian are or are prevented from dealing with certain matters for factual or legal reasons. This is the case, for example, if only part of the parental care is suspended or withdrawn. The rights and duties of the supplementary guardian are limited to these parts of personal care or property care when he or she is appointed.

If the care of property is the responsibility of the supplementary guardian and the care of the person is the responsibility of the parents or one parent (or vice versa), the family court decides if a pending decision affects both areas and the supplementary guardian and parents cannot reach an agreement.
If a supplementary guardian has been appointed for a specific area (e.g. for a decision on residence) and the guardianship has been transferred to another person (or association or youth welfare office) by the family court, the rights and duties of the supplementary guardian are not restricted by the guardianship.