So my parents are divorced but on friendly terms. My mother is re-married but my father is not. I'm not sure how they should be introduced at the reception. Ideally, I'd rather my mom and dad just walk in together, but would it be rude not to include my step-father? He and my mother have been married about five years. However, I don't want my dad to feel weird walking in by himself as he doesn't have a girlfriend. Advice?