Ok, the below code should work for you, assuming
ManualEntryForm
is the name of one of your Forms and the code is placed in the MDI parent. I don't know how else I can be of help.
foreach (Form child in MdiChildren)
{
if (child is ManualEntryForm)
{
child.Activate();
break;
}
}
if (!(this.ActiveMdiChild is ManualEntryForm ))
{
ManualEntryForm form = new ManualEntryForm { MdiParent = this };
form.Show();
form.Focus();
}