Will this be the year?

Every year at Christmas we have a big dinner with my in-laws. My brother-in-law generally brings his girlfriend. They have been together for about 5 years and neither of them are very young. This makes each holiday interesting because secretly we all are expecting them to announce their engagement at some point. My wife wouldn't mind seeing one of her brother's get married but she isn't particularly interested in having to buy bridesmaid dresses or participate in a wedding. Given the dynamics of her family it goes without saying that my wife would be expected to be part of the wedding party. What we secretly wish for is a simple announcement that they have eloped. This would make so much simpler. Our family could simply get together for a celebration of their union without all the fuss and expense associated with a big wedding.