say hello to (someone) for (one)
To pass along one's greetings and well-wishes to someone else on one's behalf. Be sure to say hello to Gerald for me when you get there! You're going for an interview with Stephen Leicester and Mary Robinson? I haven't seen them in ages. Please say hello to them for me, would you?
Say hello to someone (for me).
Please convey my good wishes to someone. (The someone can be a person's name or a pronoun. See also Give my best to someone; Remember me to someone.) Andy: Good-bye, Tom. Say hello to your brother for me. Tom: Sure. Bye, Andy. Sally: Well, good-bye. Mary: Bye. Sally: And say hello to Jane. Mary: Sure. Bye-bye.