Kelly Clarkson is keen to start a family with her husband-to-be to keep his daughter happy.

The singer will wed fiance Brandon Blackstock later this year (13) and his 12-year-old kid is already looking forward to becoming a big sister again.

Clarkson says, "Savannah is like, 'I want a little sister'. She's so excited."

And the Since U Been Gone hitmaker is getting serious about motherhood: "It's all about just making my body the most healthy inside out. And I'm reading all these books."

But, in the meantime, she's enjoying being mum to Blackstock's two daughters, adding, "They are so awesome. I lucked out, 'cause I know - I have friends, people who have stinkers. They get married, and it's like, 'Oh!'"