Kimberley Walsh finds it stressful parenting three boys. The Girls Aloud singer welcomed son Nate into the world with husband Justin Scott last June and says he has added to the challenges of looking after her other sons – Bobby, seven, and Cole, five. Kimberley told New! magazine: “It’s always fine line because you’re worried they’re going to do something that just pushes it that bit too far into the danger zone, but you don’t want to hold them back. “I know what I’m dealing with now. It’s my third boy and they all like doing the same things, which is one good thing. They like being messy and…