We have had some remarriages in our family too. We live very close to my daughter's kids. They all call me Grandma and call my husband Grandpa (even tho is not related by blood to them) But, they have Great Grandparents etc. that they don't see as often and they call everyone Grandpa (last name) or Grandma (last name) When I send things to my stepdaughter and her kids, I sign "from Grandma Wheeler" because they live close to one of their other sets of grandparents. This way, we all know which person we are talking bout.