At the wedding of a friend a few years back the bride shared a special dance with her mother and halfway through the dance her sister joined in.
The bride's parents divorced when she was little and her father was more out of her life than in so she decided it was important to honor her mom. (Dad walked her down the aisle and she did the father-daugher dance too.)
On the radio today a DJ asked listers to call in with their favorite moment at a wedding and one woman mentioned that she loves special dances and specifically mentioned a brother-sister dance. I've never heard or seen this but it's similar to what my friend did and I think it's a beautiful idea.
A wedding is a wonderful celebration and there aren't many opportunities in life to honor and give thanks to those important to you. Talk to your band or DJ about including an additional special dance in your reception but remember to keep it short - maybe even have it be not even half a song and then invite everyone else on the dance floor.
Yes, it's a special moment for you but after about 30 seconds your guests will lose interest and you don't want bored guests at your wedding.