Never saw that - I only thought it was 2, but if it was all of them then it makes it even more silly !
I went looking for the programme on YouTube but could only find the beginning http://www.youtube.com/watch?v=GGbggqhgRsI
but I'm pretty sure they were all at the wedding, although they can't have met up too many times over the years as Claire was introducing them to her husband at the wedding.
I never saw the whole Steps Reunion show, I saw the second episode a couple of weeks ago and I think the last one is on Pick Tv today, so will have a look at that. I guess they make out like they haven't seen each other for dramatic effect, it wouldn't be too interesting if they said 'yeah we've all sorted out our differences already'