There's nothing stopping you from changing the page size in the Idea Studio and drawing the HDV widgets, so I assume that you're looking for a way to do this dynamically, adding up to 7 widgets as needed.
(Although, I have to wonder why this is better than separating the graphs in one HDV...)
The solution is to do it the same way a station tag manages multiple pumps. Create them all on the page and then use expressions in the Opacity property to hide the ones you don't need in a given instance.
There's nothing stopping you from changing the page size in the Idea Studio and drawing the HDV widgets, so I assume that you're looking for a way to do this dynamically, adding up to 7 widgets as needed.
(Although, I have to wonder why this is better than separating the graphs in one HDV...)
The solution is to do it the same way a station tag manages multiple pumps. Create them all on the page and then use expressions in the Opacity property to hide the ones you don't need in a given instance.