The last invitation can say: “Did you figure out Blue’s Clues? Yup!! You’re right, kid’s name is having a birthday party”, then write the date, time, address etc. What could Blue want you to do? Come to a Birthday Party! But for who?”
Third Clue: Print out a picture of your kid with his/her face cut out and you can say something like: “Sit down in your thinking chair and think, think, think….