Three men each have two sons.Every evening they all go to a restaurant for a meal.They always sit at the same table.There are olny seven chairs.But they all have chair.The relation between then is______.
翻译：
三名男子各有两个儿子.每天晚上他们都去一个餐厅吃大餐.他们总是坐在同一桌上.只有7 个椅子.但他们每人都有一个椅子.他们的关系是______（用英文） .