You could modify the constructor of
Form1
to accept a boolean value setting the visibility of the button.
Status:
public Status(Form1 _f1)
{
InitializeComponent();
}
Form1 f1;
private void Open_Click(object sender, EventArgs e)
{
f1 = new Form1(this, false);
f1.ShowDialog(this);
}
Form1:
public Form1(Status _f3, bool buttonIsVisible)
{
InitializeComponent();
this.f3 = _f3;
this.button1.Visible = buttonIsVisible;
}