Growing Pains! Blake Lively 'Too Big' For 'Sisterhood Of The Traveling Pants'

There may be a tear in the fabric of The Sisterhood of the Traveling Pants.

While Amber Tamblyn, Alexis Bledel and America Ferrera are all on board for another installment of the beloved chick flick, RadarOnline.com has learned exclusively the friends and co-stars are worried A-lister Blake Lively has gotten too big for their britches!

“Amber and Alexis are shopping a great script, but studio honchos want to make sure Blake is involved before giving them the green light,” a source told RadarOnline.com.

Lively, 30, has moved on from her Traveling days, both professionally and personally. She’s currently busy promoting her upcoming crime thriller A Simple Favor, not to mention raising two children with husband Ryan Reynolds.

But even if she does agree, will her diva demands make her childhood friends regret the three-quel?

“It really all hinges on Blake: she hasn’t said no yet because she knows fans would love it — but she hasn’t committed to the movie, either,” the source confessed. “One thing is for sure, if Blake does sign on, everything would have to be on her first-class schedule.”