The Donna Reed Show (1958)

S5E20 A Way of Her Own

A young girl named Trisha trails the Stones back from the park, claiming she belongs with them. After an extensive search for her biological parents, her uncle shows up. He sees how much Trisha enjoys being part of a family and notices the Stones have grown attached to her. He makes arrangements for her to continue living with them, officially adding her to their family.