Nicole Kidman's two-year-old daughter is excited to be a big sister.

The 'Rabbit Hole' actress and her husband Keith Urban recently announced the birth of their second child Faith Margaret, who was born on December 28 last year through a gestational carrier, and though the couple are much busier looking after two kids, they are delighted at how their elder girl has bonded with the baby.

Nicole said: "She's so into Faith and she's crazy about her. We really wanted Sunday to have a sibling, you know, so, so now we've got Sunday and Faith Margaret.we've got our hands full! We're really happy."

Nicole and Keith, 43, surprised the world when they revealed the birth of Faith Margaret on January 17 and the 43-year-old actress - who also has adopted kids Isabella, 18, and 15-year-old Connor with ex-husband Tom Cruise - revealed they kept the news secret to "protect" the newborn.

She explained to US TV show 'Access Hollywood': "We just decided this was our thing together. It kind of just perpetuated itself. And it protects her and it protects everyone in the situation."

The couple also revealed the inspiration behind the baby's name, admitting they needed a lot of "faith" that everything would go well in the pregnancy.

Keith said: "Just the way she came into our world - we needed to have every bit of faith we could muster.

"It was completely out of our control. We just kept saying, 'We gotta have faith, we gotta have faith. She's going to be fine.'

"And we just thought, 'What a perfect name for her.'"

Nicole added: "Margaret is the name of my dad's mother, my grandmother. She had her last baby when she was 49, so, she's my inspiration."