Hi,
I had a related problem (not similar) and found a solution: Grafana custom time range for custom Graph Panel - #2 by asieroyan
Not implemented features like this require to get into the code and modify the built in panels or even creating new ones from those.
In your case, the zooming problem might be solved in the onPlotSelected() method in graph.ts file (grafana → public → app → plugins → panel → graph) and the secondary time range in the addTimeAxis() method in the same file.
Feel free to ask for more info.