So you would deal with minor issues, similar to how I would with SD? The thing is, in a step situation, there is often a parent who doesn't 'approve' of the steppies role in the Childs life and is saying to the child that they can simply ignore that adult.
I'm fortunate un that this hasn't happened in our case, but it takes a whole village to raise a child and a stepparent is, similar to a teacher, aunt, uncle, grandparent or whatever, simply another person who can add to that Childs life.
A child is not an adult, and so shouldn't be expected or allowed to choose the people who are involved in its raising.
I feel very strongly that teachers should be allowed to teach, and part of this is allowing the teacher to maintain discipline in the classroom. The parents, from what we read in the press who jump in, and take the Childs side, without a full appreciation of the situation, or who simply refuse to understand that their child can be in the wrong, or deserve the sanctions imposed by the school, undermine the whole teaching process.
The teachers I respected most at school were those who kept discipline, and indeed I kept in touch with many of them.
As a teacher, its not your job to be liked, and as a parent, its the same thing. an adults role in a Childs life is to give them the skills they need to live their lives as a productive, functioning member of society. I would not stop and aunt, uncle or whatever from disciplining my child in loco parentis, I don't understand how a stepparent is different.