The situation: Much like the giant pink diamond that Ben Affleck gave to Jennifer Lopez all those years ago, the middle-of-the road MOG is a much coveted, yet rare species. She is instinctively supportive of the union and involved in the planning process to just the right degree.
I've witnessed firsthand the power of the Happy Medium MOG, since my best friend wisely became engaged to the son of one of these women. From the very beginning, the MOG in question, Patricia, has provided assistance and opinions when requested, and she even accompanied her son on multiple shopping trips to pick out the perfect ring. She also mysteriously senses when her DIL needs her to lend a hand, and it doesn't hurt that she sides with the bride whenever she has a conflict of opinion with the groom (smart lady, huh?). Most importantly, she has the perfect attitude about the nuptials, consistently maintaining that she "just wants Ashley to be happy and have her perfect wedding day."
So, whenever you feel the urge to display stereotypical MOG behavior, take a deep breath and try to be as gracious as Patricia. Trust me, it'll pay off in spades in the long run -- particularly when grandkids enter the equation and it becomes truly necessary for everyone to get along.