>> good job. >> reporter: tristan and andrew have come to this sprawling california dude ranch today for one of many visits throughout the year. >> one of the best things is tristan will call me on facetime and share a song he just learned on the piano. that's just something special. i know he would have shared that with his father. >> reporter: you see, tristan's father, heath kelly, isn't able to talk with him about the very dr dreams he inspired. >> my dad was in the army so i just feel like i want to be an army officer like he was. >> reporter: heath kelly died shortly after tristan was born. >> heath always wanted to be a dad before we got married. this is our first baby and anytime -- any spare time he had was really devoted to being with her. you know, and also with him too because, you know, he was born in july and unfortunately he passed in september. >> reporter: heath kelly spent years overseas on active duty and then became a major in the national guard sohecould be closer to his wife and children. but soon after, a gunman opened killing kelly and three others