DEAR ERIC: About five years ago, my sister’s son was married. When we arrived at the wedding, the bride and groom had set up three special tables. One was for the bride’s parents and their siblings and children, a smaller family. The other two were for the groom’s parents and their siblings and children. Imagine my shock and surprise when all of my siblings and nieces and nephews were sitting at the two tables for the groom’s family, and I was seated at a different table with our cousins. In my place at the sibling table was one of our cousins. So, I spent the wedding sitting with my cousins, …