Whose dog is it?

[Catherine]

Cindy Gutwein had a Staffordshire Bull Terrier called Zamboni. As a responsible pet parent she had him microchipped. He was stolen from her 7 years ago.
She has never stopped searching. She has kept her microchip info current. Zamboni was found wandering in a small city south of where he was stolen. A veterinarian called  Gutwein to say he had her dog. Before she could pick him up another family put in a claim and had pictures to prove the dog had been with them for years. Animal Control turned the dog over to the family who had him all these years. Gutwein still wants her dog back and the microchip is proof that he is her missing dog.

https://www.cbc.ca/news/canada/manitoba/...-1.5641126

It is not clear yet how the family that has the dog actually got him. It doesn't appear that they stole him. They have had him as a family pet for years and the whole family loves him. He is actually Gutwein's dog and she does still want him back. If it goes to court it may take years, but she could actually get him back.
The family Zamboni lives with are the family he has known for years. The children grew up with him and he loves them.

Who should get the dog?