How to refresh a current form in C#?

How to refresh a current form in C#?

I am creating a multiple form windows application using C#, I have two
form one Parent form and a child form.
From parent form I called the child form to add a tree node in the parent
form treeview. After entering the details in the child form and pressing
"Add" button I want to close the child form and want to add the tree node
in the treeview dynamically inside the parent form.
The value is passing perfect, I am using properties for the transfer. Rest
by using this.Show() another parent form opens up. I have already tried
Invalidate() and Refresh() but the treeview does not get updated.