Finding your place in a new family can be challenging for a new step parent. Knowing that your new, sometimes instant, family has accepted you can go a long way in finding happiness and respect. We feel like Stad helps bridge the gap between being just some guy and Dad, because you're neither. Step parenting is the toughest position to be in and to become a Stad or Stom you have to earn it you don’t just get handed the title. 
In 1998 I too had this same challenge and struggled with defining my role with my step son, and the biological father. My step son and I had a sit down one day and he came up with Stad. He has been calling me Stad since then and I truly feel it has helped us grow closer over the years. Give it a try, sometimes it takes on the first try other times it takes some effort to make it stick… Good luck and happy parenting….