the hardest thing, in my experience, is to get parents, siblings, aunts or whoever is in charge of the child to stay out it. When I'm shooting a child, I want to be the only one talking to her or else she's distracted by everyone else and will never look my way.
I recommend letting her get comfortable in her surroundings and just shoot her doing her thing, then, occasionally, call her name, talk with her, bring a toy that will get her attention and cause her to come and see me. Bribery with candy often helps. Bubbles can be a great fascination.
Good coaching of what you want, exactly, for those caregivers is the most important thing. Well, and shooting her at a time of day that she's happy at. If golden hour is good for her then great, if it's not, no amount of sweet light will give you a good shot.
But the main thing is to get the parents to shut up! Good luck!