The 'Music' hitmaker's 14-year-old son Rocco previously joined her on stage during her 2012 'MDNA' tour and though he will be on the road with her for her 'Rebel Heart' concert series - which kicks off in Canada next month - he only wants to help out backstage. She said: "I think he's probably gonna work behind the scenes. "He's not interested in performing on stage with me right now. There's way cooler things. Your mom is not that cool when you're 14." The 56-year-old star - who also has daughters Lourdes, 18, and Mercy, nine, and another son, David, also nine - has been spending 10-12 hours a day preparing for the tour and even has an aide following her around to remind her to stay nourished. Speaking to Andy Cohen for Entertainment Weekly magazine, she said: "I call her the food police. ?'Are you eating? Did you drink enough water?' I'm like, 'B***h, get off my pole!' " While Madonna