Sometimes, a person other than the biological parent will seek custody of the child. This can be due to some unfitness of the biological parent, or special circumstance where the child has lived for an extended period with the third party.

A third party could be a family member or a friend or a step-parent or a significant person in the life of the child. These cases require special handling so that the rights of the parents and the rights of the third party are properly balanced.