The Minute Minders by Mary Murphy
Meet Stevie and her father: they're fidders - tiny people that work alongside humans, helping them out with their problems. But when they team up to help Sandra May, a little girl with some big issues, they'll need all of their powers of persuasion and patience to help her work out the best ways to behave. I'm Stevie Clipper. Me and my dad, we're fidders, and it's our job to help humans. Humans can't see fidders, and we can't let you know we exist. That's the rule, anyway. But me, I'm not so good with rules. Especially when a human I care about is in big, big trouble...