Flash thru umbrella or into it?

Motivated by my first grandson, I am trying my lighting gear for baby and family portraits.

How does this sound? One 550EX fired into an umbrella for a background/hair light and my other 550EX fired thru an umbrella for a fill light? (using a ST-E2 to fire them)

They live in San Francisco and will be here (Minnesota) for Christmas, so I would like get some nice shots while they are here.

So far I have been shooting full auto everthing, but would like to learn to control the flashes. I have years of shooting experience in natural light but only very limited use of flash.

I'm guessing placement of the lights is more important than the amount of light, as I can pp exposure a bit.

Any suggestions?

Thanks in advance.

That's basically what I'm doing, with my 430EX & 430EX II. I bought a cheap umbrella setup on Ebay and so far I'm really happy. Granted, I've only tried a few flash setups, but the shot-through setups seem to be very popular. Though not as popular as full-size kits

Anyway, a lot of folks are very happy doing it this way, I'm getting there and hopefully you will be there too.

dan