’There’s a flow of information in this family you’re not privy to," one of the 8,000 siblings in ABC’s big-deal Brothers & Sisters tells another one.

And if someone in the family doesn’t get the information, what’s a poor viewer without a scorecard to do when the show premieres tonight at 10 on 6ABC in the luxurious post-Desperate Housewives slot?

This is ambitious family drama, maybe too ambitious, with a startling cast and classy writing from distinguished playwright Jon Robin Baitz. But at the same time it busts the verbal boundaries, it seems strangely derivative.

Is it thirtysomething? Ken Olin’s an executive producer, and Patricia Wettig plays a mystery woman, not a cancer patient. Is it Sisters? Well, no, because there are some brothers. But the family’s rich, and there’s an awful lot of soft pizzicato soundtrack music.

It’s not The West Wing. Everything is quieter and the script is much less obvious, but politics divides this family, and politics is the career of the lead character, as much as there is a lead.

She’s Calista Flockhart, née Ally McBeal, now Kitty Walker. She’s a conservative radio host who’s moving up to TV, where she’ll sit in a red chair and yell at the handsomest of devils (do you think they’ll fall in love?), sitting across from her in blue. She has returned home to California to consider the job and celebrate her 39th birthday.

She tries to yell at her family, too, especially Ma, who’s having none of it, but who nonetheless blames her right-wing daughter for supporting her immature son’s sojourn with the military in Afghanistan. Sally Field plays Mommy Nora. Betty Buckley did at first, but she got fired.

Several people have gotten fired from, or left, Brothers & Sisters, which has been reshot and re-cast and remixed and has a little bit of the taste of that soup that’s made by too many chefs and is a minor specialty at ABC and Disney. What did happen to Commander in Chief last year, anyway?

Baitz is a theater guy. Marti Noxon (Buffy the Vampire Slayer) was brought on board for her TV expertise. "Creative differences" ensued. The new executive producer is Greg Berlanti from Everwood. Though Berlanti’s got great credentials, it appears to be a bad choice. Baitz and Berlanti know family stuff squared, but Brothers & Sisters could use a little of Buffy’s flash.

There aren’t 8,000 sibs, only five: Kitty; Justin (Dave Annable), the youngest brother, who came back messed up; Sarah (Rachel Griffiths), with marital problems; Kevin (Matthew Rhys), gay and manless; and Tommy (Balthazar Getty), who seems normal in the first episode, but who, ABC promises, will turn out to be a womanizer. Most of these relatives have spouses or lovers, too. Kitty’s birthday dinner has 11 grownups and a couple of kids, and that’s too many.

If Flockhart, Wettig, Griffiths, Field and Getty don’t give you enough to watch, Ron Rifkin plays crafty Uncle Saul. He and Daddy Tom Skerritt are doing bad and secret things to the family company’s cash flow.

Some of the star-studded casting seems a little weird. Flockhart makes an awfully wispy right-wing ideologue, and Field, though she’ll be 60 in November, isn’t much of a matriarch. It’s possible, though, that the show will make some points by casting against type. A physically fragile TV smartypants, for instance, makes a nice contrast to the big blowhards who pollute the real airwaves.

The dialogue is richly understated. "We fight," Nora says to Kitty. "We fight. It’s not the end of the world."

"Two little kids... ," laments businesswoman Sarah about her marriage. "Too much management. So little touching."

But after all the reworking, there’s still 40 pounds of drama in a 20-pound bag, as confusing as it is magnetic.

A soup with a million ingredients, simmered long enough, can be delectable. Brothers & Sisters has so much potential, it might improve if ABC leaves it on the stove. But a big early tuneout by frustrated viewers could scotch the recipe and leave this family’s fortunes unfulfilled.