Our 2.5 year old son uses a baby voice and whines most of the time. I try to say "I can't understand you" or ask him to re-phase or use a different tone and it just doesn't seem to change his behavior. He also says "he's a baby" not a big boy. He is our youngest of 2 kids and our daughter is 5 years old. They frequently play family and he is the "baby" in their family pretend game.
What should we do about the whining and baby talk? Should I not allow the pretend game of family with him as the baby?