Combined bubble/shape map or custom map overlay on...

Hello,

I'm trying to find out if the following is possible to do in Power BI. We want to be able to plot all of our projects across England on a map, with differing sized bubbles dependent on the number of projects we have with a certain organisation. We have been able to do this with the standard map visual and the ArcGIS map visual. However, we would like the background of the map to be more like the shape map, with the country split up into ICS areas (England's health and care areas) so that we can also see how projects fall across ICSs. I've been able to build just the shape map (image below) for the ICS areas, but can now only colour the shapes based on the data, rather than being able to overlay bubbles for the projects over it.

Is there any way to combine a shape and bubble map, or otherwise add a custom overlay to the map background of a bubble map to show the boundaries of the different areas?

Thanks in advance!