Note to the “90210” writers:

The Blendeds are not the Plastics.

And Ryan is no – I repeat, NO – Dylan McKay.

Yes, it was recycled plots galore on “90210” last night, starting with Naomi trying to fit in with a new clique, a device completely ripped from the 2004 Lindsay Lohan flick, “Mean Girls.”

(And on a show where the main actresses have alarmingly skinny physiques, it probably isn’t too smart to be promoting a diet that consists of only blended beverages.)

Then the show reached back in time by having Kelly and Brenda at odds over yet another guy, proving these two haven’t quite left that West Beverly rivalry behind them. And quite frankly, I can’t figure out what’s so intriguing about Ryan that he’s worth fighting over. Dylan, at least, was a surfer. He had great hair. And sideburns. A criminal father. A melancholy nature. Need I go on?

Anyway, we picked up right where we left off last week, with the sudden arrival of Sean, the love child of Harry and Tracy. We learn that Soldier Boy had a pretty terrible upbringing with his adoptive family in South Carolina, and he’s on military leave from a tour of duty overseas.

The Wilsons take Sean in after it’s pretty clear that insane Tracy’s idea of bonding is to take Sean to Nobu and every other overpriced sushi restaurant in L.A. Harry’s attempts to connect with Sean raise a whole bunch of issues for Dixon about his own adoption, his biological family and race – which I was glad to see the show bring up – and he starts to flirt with a cute, random cheerleader who seems to be the only other black kid in school. (Watch out, Silver…)

Meanwhile, Annie’s hookup with Ethan and breakup with Naomi has turned her into a catty bee-yotch, but she’s so sad she can’t even come up with any good put-downs. The best she can come up with is trash talking Naomi’s Uggs. Hello, Annie? Naomi’s wearing a hideous, lowcut, hot pink lace top that makes her look like a Victorian whore, and you’re focused on her footwear?

Speaking of Naomi’s atrocious fashion sense, those Blended girls must be blind if they think she accessorizes well. But they assign her a few tasks before allowing her to join their little group – Naomi’s going to have to fit a lot more black into her wardrobe – like programming their Sidekicks and getting them into the hottest restaurant in town.

Which just happens to be owned by Ozzie’s father. Score!

Ozzie sets Naomi up with a table, but not before making her promise to “owe him one.” That later translates into a hot kiss between the two, even though Ozzie really wants to embarrass Naomi by having her kiss the lacrosse team mascot at the big championship game. But, gasp! The mascot turns out to be Annie! Like, ew, they’re mortal enemies. Wow, way to bring a girl down. Lame.

Then there was the Brenda-Kelly business. Kelly’s “friendship is like a potted plant” lecture to Annie and Naomi got her thinking about her own tense relationship with Brenda, who hadn’t been returning her calls.

So she shows up at a play Brenda’s doing – which looked like it was being performed in a hotel conference room – to invite her to lunch. And Kelly actually GAVE Brenda the potted plant, which was incredibly weird and uninspired.

At lunch, Bad Girl Brenda let Kelly have it: She just doesn’t understand why they should continue to be friends when they have nothing in common anymore. Snap! (Annie, take notes on how to hurt someone.)

Yet the two reunite in the hospital when Brenda falls off the stage during a performance of “Macbeth” – uh, random? – and Kelly is her emergency contact number. She confesses that she was really trying to push Kelly away because she didn’t want to tell her she slept with Ryan.

I knew it! And from the looks of the upcoming trailer, my prediction that Brenda’s pregnant appears to be right on the money.

One other thing we learned in the episode’s final moments? Sean may be a scam artist.

He made a suspicious phone call to someone, diabolically chuckling how he was making himself “right at home” at the Wilsons. Is he REALLY Harry’s son? And even if he is, is he just out to swindle the family out of some cash?

We won’t find out until the new year: The next new episode isn’t until JANUARY 6!

Man, not even a Christmas episode? Bad form, “90120.” Bad form.

(Photos courtesy of the CW)