When I explained our process, I mentioned the principles that we'd be working with. I think it's worth going through them and explaining a bit about what they mean in practice.
The first is that "Whoever comes is(/are) the right people" - yes it's a bit confused grammatically, but even linguistic dictators are welcome! it's a reminder that for the time we're together, we are the right people to be coming together to work on this. The great thing about modern technology of course, is that you can always "bring people into the room" with a video call or a lifestream but it's also good to just accept that the people who can best work on what we're working on are somewhere in the room.
Also it's tempting to think that "someone" should have made sure more people (or sometimes fewer people) were there. You can take responsibility for getting more people in the room, if you're worried about this - don't wait until the day itself, now's your chance - have a think about who you'd like to see there and invite them.
All of these principles are there to help us remember to stay in the present while we're in the space and to focus on what is happening rather than what isn't. It can be easy in large gatherings to spend time thinking about who should be there who isn't - oh, if only so and so were here, she'd know what to do. Well, so and so isn't here, but you and I are, so what are we actually going to do? Also if we're used to being in spaces where
You may also find that there are people you wish weren't there! If only they hadn't managed to get out of bed this morning... Consider that they might, of course, be thinking the same about you.
All the principles work at the level of the day and the level of the session, whoever comes to your session are the right people, welcome and accept them as you're being welcomed and accepted to the day as a whole and trust that if there are people on the other side of the room who really need to be in your session, they'll find their way to you in time.
It's all going to be OK, we'll have the right people to work on things even if one of the things is a long list of all the people who must be at the next one.
everyone get your tickets!