Hi Viv,
The marriage contracts I found in the Northside Sales index had both groom and bride's names bracketed together followed by Contract and then the number of the deed. These are in sections headed "May 1723", "October 1723", "May 1724", etc., under the parish.

J. R. Roscow wrote in that article (last message) that "A Manx marriage contract was an agreement between the families of the groom and the bride, setting out in detail how much of the land, animals and other property would belong to whom, and when the transfer would take place". So I think you would need ownership of land or a house on one side at least, but sometimes the holding was very small.
He gives a lot of interesting examples, with names, places and dates, and also writes about divorce and dowries.

Sue