One way would be pass an instance of the MainForm in either the
constructor or in a seperate method to the child forms.

Something like this
ChildForm cf = new ChildForm(this);
this.Panel1.Controls.Add(cf);

and inside ChildForm
public ChildForm(Form parentForm)
{
    parentForm.Text = "Whatever";
}

A cleaner approach would be to use Interfaces, but the above will work
too, let me know if you have any problems getting this implemented.

Sijin Joseph
http://www.indiangeek.net
http://weblogs.asp.net/sjoseph