Passing data between active forms (WinApp)

Question

Hi guys, I have a headacke because of this, I have child form who needs to receive data from the list doubleclick event inside his child form. I will explained with more details if you have not got it. I have a form who needs a piece of data as result of a consult. This consult is made with a child form called (search for customers), the result of this consult is showned in a list, now, with double click event I have the selected data I want, but I don't know how to make the first form can receive this data after the child form have closed. Even doesn't matter if the child form is closed or not, I need the data to fill my Customer information... Please for help.. Thanks a lot