need help on MDIform

I have one form which is MDIParent (formA), now i call a MDIchild (formB) from formA.

code:
Dim f as new formB
f.MDIParent=Me
f.show()

On formB, i have a button to call another normal form (formC).
My question is, how to make formC as child for formA?

thank you for your replies... i really appreciate it....

Just set formC to have the same parent as formB. So from within formB you would use this code.

Dim formC As New Form()
formC.MdiParent = Me.ParentForm
formC.Show()

thank you for the code.... and my project now run smoothly....

thanks....