Teaching a new dog old tricks?

Today my sister in law Kortney and her one year old daughter came to hang out with Dalin while I was gone for a little bit. When I came home Dalin said, "Mom watch. 'Alia do nothing.'" Alia just looked at him and he gave her a goldfish cracker. Then he told me, "See she does tricks if you give her goldfish." I guess he was practicing this trick while I was gone because Alia was being a little cranky and Kortney told me Dalin would say, "Stop crying Alia" then give her a goldfish and she would stop. How do I get that to work on Dalin:)