Designer support for nested controls

Hi - I have a simple custom control "BoxHeader" that simply wraps a bunch of controls with a header.

However, when I add a GridView to the contents of this BoxHeader and switch to design-view I cannot see any of the designers inside the custom control. I have tried adding the "ControlDesigner" attribute to the BoxHeader, but this will only show the HTML not the control designer for the GridView.

Can anyone point me in the right direction?

 Cheers,

Thomas
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