"Step-grandparents"

My husband's parents recently divorced and both are now remarried. We are especially unfond of his dad's new wife, who is manipulative and conniving. That being said, we want our daughter to grow up showing respect to her actual grandparents and their spouses, even when we don't necessarily think they've earned it. We are strongly opposed to assigning "grandparent names" (like Grandma/grandpa, Nana, Pop, etc.) to the new spouses of my husband's parents, but we also were both raised to not call our elders by just their first name. Most times, we would put Ms. or Mr. before the names to show respect. But for "step"-grandparents, that seems too formal Any suggestions on alternative names?