Hover event of multiple points at the same coordinate in different traces

I have a plot where I place several traces one on top of another.

Producing an output like this:

However, the hover event is only triggered for the topmost trace, which in the case above is scatter plot (with triangle markers) and in the case of the contour lines, only for the green contour.

What I want is for Plotly.js to add include all the points at event coordinate in the event object.

Is that possible?