Diana Ross will get custody of Michael Jackson's children if their grandmother Katherine Jackson dies.

Although Prince Michael I, 14, Paris, 13, and nine-year-old Prince Michael II, also known as 'Blanket', are now in the custody of Katherine following Michael's death in July 2009, the 67-year-old soul singer was named in his will as a guardian and will take responsibility for them if anything happens to his mother.

A source told media: "Diana has made no moves whatsoever not to fulfil her role that Michael intended for her. Michael didn't trust anyone in his family besides, his mother, to raise the children. Michael loved Diana and chose her for a very specific reason."

Although the 'Thriller' singer wanted his 80-year-old mother - who will turn 81 on May 4 and currently has a live-in carer - to care for his children, he was aware this would not be a long-term solution and so named Diana as a second guardian.

The source added: "Katherine is a very doting, loving grandmother. She just isn't getting any younger and that is why Michael named a second guardian."

A friend of Diana's said: "She will step in if there's an immediate need to do so."

Diana has five children: Rhonda Ross Kendrick, 39, with Berry Gordy, Tracee Ellis Ross, 38, and Chudney Ross, 35, with first husband Robert Ellis Silberstein and Ross Arne Naess, 23, and Evan Ross, 22, with Norwegian shipping magnate Arne Naess, Jr. who died in 2004.