The country star, 37, and his wife Cassidy will be expanding their brood this fall by welcoming a sibling for big sisters Evalyn Day, 4½, and Jordan Catherine, 2.

And the parents are already planning for being outnumbered.

“So my wife and I will be changing our family defensive strategy come the fall. Switching from MAN-to-MAN to ZONE. #3! Advice @thetimmcgraw?!” Bentley announced on Twitter early Thursday.

He says it’s too early to tell whether it’s a boy or a girl.

“They are thrilled beyond belief,” Sugarland’s manager, Gail Gellman, tells PEOPLE.

The Grammy winner, 37, is due in November, Gellman says, which will coincide with the couple’s first anniversary since their sunset wedding ceremony outside Nashville, in which Nettles dazzled in an Alexander McQueen gown at a chapel nestled in the foothills of the Smoky Mountains.