Hi Jody,
I guess you do something similar to the following:
Form form2 = new Form();
form2.TopLevel = false;
nTabPage1.Controls.Add(form2);
form2.Show();
To make the form to fill the whole area you can add the following:
form2.Dock = DockStyle.Fill;
form2.WindowState = FormWindowState.Maximize;
However, my suggestion is instead of using this second form to use UserControl.
I hope I understand the problem correctly in order to suggest you a correct solution.
Regards,
Angel.