You can say now what you want them to call you, but they sorta choose and it sticks. Mine call me Grandma and papa. When we were expecting our first grandchild my husband had it in his head we were not going to be called anything but Grandma and Grandpa, no Nana(like my sister) or MiMi (like my other sister) and no Papa. Now that he is Papa he is perfectly content with it. My advice just go with whatever they call you and love every minute of it.