Popup window data to be display in parent window

See more: (untagged)

I was developing a application using wpf & C#, I was stuck at some level
when I enter data in the popup window , it was not reflecting or updating the datagrid in parent window. Instead when I close popup window it updated the parent window datagrid,
My problem is that I want to update the parent window datagrid without closing the popup window. I am using add button and close button in my pop up window. I will show the data that I entered in the popup window.

How can I achieve this.

What I have tried:

(see above) ... nothing, actually.