give a solution for creating two or more child forms in a mdi form

//******************************************
//          inside child form
//******************************************
this.MdiParent.ShowAnotherChild(formKey);

//******************************************
//          inside mdi parent form
//******************************************

//I find it easier to work with dictionary than with existing MdiChildren property
Dictionary<sting,form> _mdiChildren = new Dictionary<string,form>();

void ShowAnotherChild(string formKey)
{
    if(!_mdiChildren.ContainsKey(formKey))
    {
        AnotherChild newChild = new AnotherChild();
        //...
        //code to configure a new form as a mdi child goes here
        //...
        _mdiChildren.Add(formKey, newChild); 
    }

    _mdiChildren[formKey].Show();
    _mdiChildren[formKey].BringToFront();
}