How form can use in keyUp event of the parent form?

I have a problem,First, I have a parent form ("mainForm") and in this there is a KeyUp event(private void MainForm_KeyUp(object sender, KeyEventArgs e))

Second, I have child form(Frm2) than opened by openDialog command, Now I need that Frm2 can use in MainForm_KeyUp. Really, Frm2 comes to MainForm_KeyUp function, but KeyEventArgs e = Keys.Enter and not all my numbers. A comment: the KeyEventArgs Filling up by magnetic Card reader.

I'm really thankful for your trial to help!!! Soh