I remember my mom having a rule that I was not allowed to be a part of the conversation when she spoke to my teacher.
My mother's purpose was to keep me from feeling that I was the "new power" if she took my side. My mother always felt that a class runs better if the Teacher is always viewed as the authority in the class. She was probably right. Other students who's parents had opposed the Teacher in front of them, felt it fine to continuously oppose the Teacher in class; which proved to be disruptive. Such moments caused the student and teacher to have a battle for power throughout the remainder of the year. It also made room for other students to challenge the teacher. It sometimes creates an "us against them" consensus.
Another reason my mother decided to keep me out was so that if she agreed with the teacher, they could agree to a plan that would take care of the problem and keep me on the right track at home and at school. My mother would walk away with a complete picture of who I was in school. Together they could decide what was effecting me and what would be the best solution.
By keeping me out of the meeting I did not need to know which side my mom took. Afterwards though, she would always remind me of my responsibilities in the class and how to deal with my concerns for situations with the teacher.
My son was invited to come to his fifth grade conference but not his sixth grade one this year. I am fortunate that my son does not have a hard time in school - either with behavior or academics. But, I imagine if he had had problems - the conference in fifth grade would have been a bit awkward.
The space for the parent - student - teacher conversation exists, but I'm not sure if one needs to wait for teacher conferences for that to take place. That should be ongoing based upon the need!
I was a pretty bright kid. Sometimes though, when I finished my work to early, I became a bit talkative and on a few occasions I was accused of things, by other students, mostly because I was the Teachers' Pet.
No matter, excluding me from Parent-Teacher talks went a long way.
Not to mention - we really appreciate coming home after conferences and talking with our children about what their teachers said, what their strengths are, how they might improve, etc. I think our children enjoy that too.