What is the test for a third party to claim custody of a child?

Many cases have considered the difference between the claims of a third party, including active and involved grandparents, and the claims of parents. In Charron v. Vignaux-Fines, 1987 CanLII 20 (S.C.C.), the court stated that: A third person who wishes to obtain custody of a child must rebut the presumption to the effect that the parent is in a better position to ensure the child’s well being. He must establish on a balance of probabilities that the development of the child is likely to be compromised if he or she remains with the father or the mother or returns to live with them. The third person must also show that, unlike the person having parental authority, he or she is able to provide the care and affection needed by the child. EVIDENCE