Communicating with parent components

[QuasiStellar]

According to docs, child components are not to use ComponentContext's of their parents. So something like this is wrong:

class MyComponentImpl(
    componentContext: ComponentContext,
    rootContext: ComponentContext,
) : MyComponent, ComponentContext by componentContext {
    ... = rootContext
        .instanceKeeper
        .getOrCreate(...

So what is the right way of creating a communication between parents and their children? For example I want to store some configuration at the root level, so root's children (and children of the children) can use and modify it.