When kids were young, I hand wrote a letter to them. I could not recall the details, I do remember telling the younger one that his favorite toy could not make it to on Christmax day and  offered him alternative.  And asked him to promise to share with his older sister. 

Years later, they said they had wonderred how come Santa's handwriting was the same as their dad, and how could Santa knew their mannerism and manners.

Sweet memories. I wish that letter was storied away somewhere.