VB.NET Form Modal vs. Non-modal vs. Owner

I have Form1 and Form2 which should be accessible to the user independently.  A button on Form1 will open Form1A (should be modal to Form1 only) and open Form2 (accessible while Form1A is open):

        Form2.Show() 'Should be independent from Form1 and Form2
        Using frm As New Form1A
            frm.Owner = Me
            frm.ShowDialog()
            'When Form1A closed, do something with user entered data
        End Using 

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I have tried using a mixture of owner and show vs. showdialog, but if the Form1A is modal, it also blocks access to Form2.  I need for the user to be able access both Form1A and Form2 at the same time.   When open, Form1A should of course prevent access to Form1.  I realize that I could probable add code to Form1A in the FormClosing event, but I also want the code to be cleaner, and Form1A could be opened from various other forms as well.  Any thoughts on how to accomplish this?