how to open one form inside another form

Question

I have three form in windows application I want to open form2 inside first mdi Form1 then  form3 open inside form2.

 

code in First MDI from1. 

Form2 frm1 = new Form2();

frm1.MdiParent = this;

frm1.Show();

code in second form2.

 

Form3 frm3 = new Form3;

frm3.IsMdiContainer = true;

frm3.Show();

 

 above code is not work in my application.