Combining Canon flashes?

Hello all!

This is my first post on the forums although I have been watching and reading for quite some time now.

I have a 550ex and a ST-E2 that I am using with my 20d and 40d. I would like to add a 430ex ii to the combination.

My question is whether or not my 20d or 40d can receive the zoom and WB info from the 430 via the ST-E2 even though I am using the older 550ex in the mix.  If i take the ST-E2 out and the 550ex becomes the master, I'm guessing I lose the zoom and the WB? I know the 580 ii is the best choice, but I'd like to work with what I already have.

Thoughts or experiences?

B