如何将事件附加到类的已创建对象而不是创建新事件

I have 'MainWindow' form which is an MdiContainer and with a group of buttons, button1 loads 'DesignTools' form as a child form, this has got some set of buttons as well. There are some common buttons on both the forms. Attached events to the buttons on Child form and want to raise same events from the buttons of 'MainWindow'. Attaching the event to the newly created object is not giving any result, like the below. So, trying to attach the event to an already created object of 'MainWindow' , but unable to find out a way to do. I have:I have 'MainWindow' form which is an MdiContain