In a normal (1s improper) contra, you start with your partner across from you and your neighbour next to you. Anyone outside the minor set is a new neighbour / shadow / something else.
In a Becket formation, you start with your partner next to you. Who's opposite you - your neighbour or your opposite? If it's your opposite, who's your neighbour? Is it the person next to you who isn't your partner? (I have seen it used this way.)