Single button for all forms

Question

I m developing a window application for school management

In this application i m heaving a SAVE button on parent form

As i open a child form and click on save button on parent form 

the value should be saved ,Button should have an intellence 

that what form is activate and what forms values is to be saved

Please help me it is urgent

Thanx Jaish

 I m geeting an idea via your comment although It is not completely clear to me

 If would be able to send me a bit code it will be very greatful to me