Dane, 39, and Gayheart, 40, say Billie is finally warming up to little Georgina.

"Billie is being a great big sister now," Gayheart gushed to us at the Chrysalis Butterfly Ball in L.A.

"We've had a couple rough patches but she really adores her," she said. "She's really sweet. It's like her live baby doll."

That means Billie is getting more hands-on with mom and dad's baby duty.

"She helps change her diaper and give her food and put her bib on," Gayheart said, adding, "but sometimes she regresses and wants the pacifier for herself."

Meanwhile, Dane dished his thoughts about Grey's Anatomy's shocking season eight finale in which costar Chyler Leigh was surprisingly killed off.

"I wasn't [shocked] because I knew that Chyler wanted to spend some more time with her family," Dane said. "It's a tough schedule to keep up and she's been working on the show for five seasons. So I wasn't shocked. A little surprised but not shocked. We're going to miss her."

See more here:
Grey's Anatomy Star Eric Dane and Rebecca Gayheart Talk Kids—and the Show's Finale Surprise