I think I got my one-step update working. But my IRA account downloaded hundreds of transactions going back a couple of years, which has them sort of "starting in the middle"... just transactions appearing with no opening cash balance, etc. And they're all for funds I've gotten rid of.
I really want this account to start a few days ago, and forever ignore all transactions dated before April 14, 2010 I cannot find a way to delete a bunch of transactions, or to tell the update to ignore them. It would take me hours to manually delete them, and then I'm guessing it would just want to re-add them all again next time I update.