Automactically set contol value on form from another form

[James]

Hello,
Does anyone know how to get a value that is set in one
control box on one form to be automatically set to a
control box on another form once the other form is
closed. For example, what I am trying to do is set a list
of values in a combo box on one form that can be added to
by opening a second form to add/edit those values. What I
want to do though is for the last value that is typed into
the add/edit form to be set automatically into the combo
box on the first form once the add/edit form is closed.
Any help is greatly appreciated. Thanks in advance.
James