One-to-many relationship in Core Data - how is the owner object updated?

I am making an application that has two entities in the data model, with one entity having a one-to-many relationship to another one, let's say a Parent can have many Children. The Parent entity has relationships to all its children (as an NSSet-type property automatically created in the generated class file), and every Child has a relationship to its one Parent (as a Parent-type property in the generated class).

The application works as follows, first the user can create a Parent with all its properties set except that Children is automatically initialised as nil as I don't set it explicitly. This object is saved to Core Data. Then the user can create a Parent's children, and when preparing the object before saving to Core Data, I pass its Parent object to its *parent property, and everything seems to work properly - I get a parent list displayed correctly, and each parent has a list of its children displayed correctly, no crashes, everything seems to persist properly. I only save the new Child in the context and don't touch the Parent.

The question - how does the Parent entity know that it gets a new Child, when it has already been saved to Core Data before? Is it because I have an inverse relationship set, Core Data automatically informs Parent that it has a new Child, and updates the Core Data store accordingly?

Thanks for any insight on this matter. Hope I was able to express my question in an understandable way, if not - I'd love to elaborate more. The thing is that I am not sure why my implementation is working and what is actually happening under the hood.