Inheriting forms with Singleton

Hi All,
I have an MDI application where I am modifying data for a number of items that are all so similar I hope to use a single form and change the title and a couple of things on the form rather than create a bunch of forms that are all the same.  I'd also like to limit each instance of any given form type to 1.  I've tried using various forms of the singleton pattern, but it (by design) won't let me create multiple instance of the form so I tried to inherit from a base form to enforce singleton on the derived forms but was getting some weird errors that publically exposed method calls were not defined (?!)  Has anyone tried this type of thing?  I can do this with brute force looping on the MDI itself, but was hoping for something more "elegant"...
Thanks,
John