The approach you are trying to implement seems way too complex to me and I have some doubts whether it will produce satisfactory results. I would suggest you to check the WPF version of the chart control that provides built-in support for multiple Y-Axes
-- you can easily host it in a winforms application provided that you can up the project .Net Framework version to 3.5 or later.
You can check the WPF ClickOnce demo application here
as well (the specific demo is available under Chart > Features > Multiple Y Axes).