I have the similar scenario.
1. There is Parent Page, which shows list collections and provides a edit link to each one.
2. When you click on Edit link, it will open a radwindow(EditRadWindow) which contains multiple radgrids in it based on data collections type.
3.This EditRadWindow provides a feature of adding new data to existing list of data. When you click on this Add link, it will again open a radwinow(AddRadWindow).
4. I will provide some data at AddRadWindow and click on submit button, then it should pass the data to ParentWindow's corresponding grid before closing itself.
Can you please provide any solution for it.