You may want to have a read at Redux (http://redux.js.org) or any Flux type of container.
Basically, you don't propagate directly to your parent. In React there should be only one source of truth. So in your case, the event in a low level component should emit an action that will modify data in your Store/Container/Model. Then this change will be passed down (with the correct setup) as props to all of your components.
>React best practises question - At what level should event handlers be installed? At lowest level components or the highest level?
I personnally prefer when the handlers are close to the associated JSX. I doubt there is any requirement on this other than maintainability.
Basically, you don't propagate directly to your parent. In React there should be only one source of truth. So in your case, the event in a low level component should emit an action that will modify data in your Store/Container/Model. Then this change will be passed down (with the correct setup) as props to all of your components.
>React best practises question - At what level should event handlers be installed? At lowest level components or the highest level?
I personnally prefer when the handlers are close to the associated JSX. I doubt there is any requirement on this other than maintainability.