I am trying to add smart fasteners to a pipe assembly (see attached pic). Bolts are added to one end and I cannot select the holes at the other end. Smart fasteners appears to be treating the holes at one end as going all the way through to the other end. When I add a bottom stack, the nuts appear at the opposite end. What I want is to have bolts and nuts at both ends which attach the pipe ends to the pipe. What am I doing wrong?