What is the purpose of a Unity candle? Two lighted candles, one each on the bride's and groom's side represent the pairs two separate lives and families. After the pronouncement of their union, the bride and groom carry their representative candles to light the taller unlit Unity Candle which symbolizes their lives now joining as one.
You can ask ushers to distribute to each guest as he or she is seated. After lighting the unity candle the bride and groom may walk tot he first row and each light the candle of the person seating in the first row.