Based on your requirements, I can offer some lens suggestions that might be suitable for your needs.
For nature photography, it would be best to use a telephoto lens with a long focal length and wide aperture to capture splendid shots of wildlife, landscapes, and details. One lens you could consider is the Nikkor 70-300mm f/4.5-5.6E ED VR lens.
To capture your little girls as they grow up and play sports, a lens with a fast autofocus system and a decent focal length would be ideal. The Nikkor 18-200mm f/3.5-5.6G ED VR II lens is a great option to consider since it is a versatile all-purpose lens that can take exceptional photos of various subjects, including action shots.
Alternatively, for portraits of your little girls with a blurred background that enhance the image quality, getting a prime lens with a wide aperture would be the best option. The Nikkor 50mm f/1.8G lens is an excellent choice because it showcases a beautiful bokeh effect that makes your subject stand out even more.