assuming you having basic photography skill and knowing some basic camera models, then my thoughts may help to choose a camera. as you can see here, one pic taken from 35mm lens, another from 50mm lens, both on a full frame camera. both pics from close distance, then kid could be placed in a main photo frame. this kid is also 2 and half years old (acitive toddler, qualified). my suggestion is to take a wide angle zoom lens and a standard lens with a full frame camera, or a super wide angle lens with a half frame camera. do as you can to get a large aparture lens. if you think these two photos relatively fullfills your job, then this is it.