There are many different unity ceremonies. These can be just for a couple or involving family and friends.
Unity sand ceremonies, tree planting ceremonies, wine ceremonies (or any drink you may prefer).
It is suggested that this is one of the oldest wedding customs and this where "tying the knot" comes from. Braided long cords or individual coloured ribbons can be used. These are available in all colours and various materials.
Unity Candle Ceremony
Two candles are lit individually (normally bride and groom). Together a large candle is lit thus merging the two flames into one (a new flame). Members of the family can be included.