C / C++ / MFC

in the new dialog class add this function. Now the new dialogs will control that menu item in it's parent.

void MyClass::checkmymenuitem(int checked) 
{
CMenu* pMainMenu = GetParent()->GetMenu();
CMenu *submenu = pMainMenu->GetSubMenu(1); // replace 1 by the horizontal menu position
UINT g = submenu->GetMenuItemID(3); // replace 3 by the actual vertical item position
CString mnustr;
submenu->GetMenuString(3, mnustr, MF_BYPOSITION); // replace 3 by the actual vertical item position
// you can optionally change mnustr to a text here
if (checked) submenu->ModifyMenu(3, MF_BYPOSITION | MF_STRING | MF_CHECKED, g, mnustr);
else submenu->ModifyMenu(3, MF_BYPOSITION | MF_STRING | MF_UNCHECKED, g, mnustr);
}

in initdialog

checkmymenuitem(true);

then in onclose 

checkmymenuitem(false);