Form refresh

I know this question has been asked but I can't get it to work.
I have a form with a subform in it. I have command buttons in the form
header. What I want to happen is that when I select on of these buttons ,
either Customers (which has its combo box on the main form) of Inventory
(which has its combo box in the subform), and then add in the new record. I
want the prchase orders form to refresh automatically inputting the new
records without having to hit a refresh button. Is This possible and what
would the coding be. I assume it would go under the on close control.

Thanks