multiple child form with one parent in c#windows application

Hi friends,
       I m using visual studio 2010 c# windows application. i was created one parent form(mainmanu.cs). In the mainmanu form having buttons... when i clicked button the child form(form1.cs)opened. In the form1.cs, i having one button to Edit. when i click edit button it opened another form form2.cs..

        My problem is when i click first form form1.cs is opened with mainmanu.cs window. But when i click edit button the second  form2.cs  cannot open with main manu? And also having error "cannot use parent form and child form in same form"
      pls help to overcome this problem friends,



Thanks,
chiNa.