When can you start switching members? (spoilers for anyone not yet at Ch. 9)

So I'm in Chapter 9, (SPOILER)on that ship, trying to rescue Sahz and Vanille. Are you able to switch party members yet? By default there's (SPOILER)Lightning, Hope and Fang in party, but I want to get Snow in there, but I can't find any way to switch him in. Is there a way to swap party members yet? I can't see a way to do this yet, so is this the way it is for now, or is there something I'm missing?

Helppleaseandthanks.

You'll have to wait until the start of the next chapter.

BAH!

Actually it's near the end of Chapter 9. :P

ys, just before you fight dysley you get the ability to change MEMBAZ

I knew it was around the turning point of the chapter, just wasn't sure which side.

yea, you can't sub in Snow until Sazh and Vanille join back up. When you can change party members, the game gives you one of those tutorials on how to do it (assuming you didn't turn the tutorials off).