I had three.

Mary was the one my father never met. Buried in Spokane.

Laura was a well-meaning stranger. A nurse.
Dad never knew the score until he hit fifth grade. Following a parent-teacher conference, his classroom teacher hit him with, "So - you're stephcild," or something equally wickedly lame. Blended families go under the rug.
Laura died this summer. I hadn't seen her in ten years, not since my grandfather's funeral. She had cancer.
Laura bought me a Pound Puppy one year for Christmas. I named it Lady. Then she had a fight with my Dad and the presents stopped coming.
Laura was a chain smoker.

Delna's my last surviving grandparent. Turned 75 a couple of days ago, and still kicking, brand-new artificial hip notwithstanding. I visited her is the hospital when she had the inferior organic hip replaced this summer. I realized I had never had occasion to visit her in the hospital before, but I probably would once more.
She came to visit me a few weeks after I left for school. We saw American Beauty, and she said it was trash.
When I was little I would throw all my belongings in a picnic basket and head to the farm to visit Grandma and Grandpa. I would go to church with her, and if nothing was doing on the farm, Grandpa would join. I got bored easily in church. Grandma would pull a little Tupperware container full of trail mix out of her purse and slide it across the pew. This kept me from noticing the boy in the row in front of me, who was wearing girls' dress shoes, complete with bow ties.