Lionel Richie adopted Nicole Richie to help out his friends

He said: "I went to a Prince concert and there on the stage in the middle of the concert was this four-year-old kid playing the tambourine. So I went backstage and I knew the mother and I knew the father and, of course, they were having difficulties with their relationship.

"I said, 'While you are having the difficulty the kid is sitting out here in limbo so I'll tell you what I'll do, just put the kid in my house until the tour is over with and then we will sort this out later'.

"And so it took about maybe a year for me to just fall in love and she was a little button, and of course by that time I was Dad and so I said, 'OK here is what we are going to do, you're going to make everyone wish that they had adopted you. You are going to make everyone in your family wish they actually had a chance to get you back,' and that's when I said, 'Let's adopt her.'"

And the 66-year-old singer made good his promise, sticking by her when she was arrested in 2003 for possession of heroin.

Speaking on Piers Morgan's Life Stories, he said: "I sound like my father now, but I went to her and I said, 'When I was growing up I lost three friends, they were the hippest friends I ever knew in life ... I said, 'It's going to happen to your generation. I don't want you to be in that list of three because after that you'll be just fine'.

"Three months later her friend died of an overdose and I went back to her and very quietly, I was very shocked, and I said, 'I am sorry to hear that, that's one.' And sure enough, one year later the second one died and I said, 'That's two' and I got a phone call and she said, 'Dad I need help, I don't want to be the third one'.

"And I said, 'I am with you' and I cancelled the tour. I said, 'Me and your mother', who didn't get along that well, 'Me and your mother are checking into rehab with you.'"