Seats One, Two & Three

I think I've figured it out, mindful of Marsbar's comment last night.
Not trying to open old wounds, but I have to know what it means.
DB would be the new addition, MS could be one of the other two. Am I on the right track? Who is the other one?
Not trying to open old wounds, but I have to know what it means.
DB would be the new addition, MS could be one of the other two. Am I on the right track? Who is the other one?