Sandra Bullock on how she kept her new daughter's adoption a secret.

“My family is blended and diverse, nutty, and loving and understanding. That’s a family.”

Sandra Bullock has a new addition to her family – a daughter named Laila.

The 51-year old, already a mother of Louis, 5, has told People that she has adopted a 3½-year-old daughter.

The little girl, Laila (pronounced Lila) from Louisiana had previously been in foster care.

“When I look at Laila, there’s no doubt in my mind that she was supposed to be here,” Bullock told People.

“I can tell you absolutely, the exact right children came to me at the exact right time,” she adds.

Bullock adopted Louis in 2010 from New Orleans with then-husband Jesse James.

This time she is doing it solo, although she is reportedly dating the photographer who took the images for People.

The news that Bullock had a daughter has been floating around for some time. Last year there were magazine rumours that Bullock had made the new addition, but at the time she was determined to keep it private.

“You feel it’s very much like witness protection,” said Bullock.

As the little girl was in foster care Bullock feared the process would be jeopardised if the Laila’s face was snapped by the paparazzi.

“Most foster children are in foster care because they were taken from their birth homes under tragic circumstances — and the last thing I wanted was to bring more harm to her because of the nature of my job,” Bullock told People.

Her adoption nearly came undone when paparazzi photographers followed her to the emergency department at a hospital one night. The photographers captured images of Laila that they tried to sell around the world.

“The next day, I learned that a photo of her was being shopped around for sale to every outlet around the world,” she told People.

“ I had promised and legally agreed to protect her from something like this, and here I was chasing down lawyers — having them begging them to keep her safe.”

Sandra Bullock tells Ellen about her son, Louis…

In October Bullock denied she had adopted during an interview with the Associated Press.

“There is only one adopted child in my household and his name is Louis,” Sandra said at the time.

“If I had a second adopted child, everyone would be hearing about it. I would be loud and clear and say, ‘Yes, I have officially adopted a second child.’ Right now, Louis must be it.”

Now the adoption is final, Bullock can open up about her new addition.

She says that she knew she had found the perfect sister for Louis after a visit from Child Protective Service (CPS).

“There was an afternoon when we were outside and Louis saw their car pull up and he ran next to Laila and asked the CPS workers why they were there.”

“They replied that they were there to see if Laila was okay. He replied, ‘You’re not going to take her away, are you?’ And at that moment, I knew I could stop worrying about whether I had found the right match. It was obvious I had.”

Bullock, who is a single mum, says Laila has brought a touch of  “pink and glitter” to her home which is already “mixed with Legos and Batmans”.