2-ways relationship in facet for related post types, when both are in template

Hi there,
I have a weird situation. I built a facetwp filtering system for the post type "intinerary". Each Itinerary is related to a number of "city" posts.

I've created a facet with the [Itinerary] City source and all works great.

Now, the customer wants to implement City Guides and show them together with the Itineraries within the same interface.

I added the relevant taxonomies and the post type to FacetWP and that works great.
However when I select the city from the "cities" facet, it will show the related itineraries but won't show the city itself.

Here's the example:
https://dev.mundana.com/explore/?_destinations=europe&_city=1411

Is there any way to make this facet reciprocal, so that when I set it I also get the city itself in the search results? I assume some kind of filter on the facetwp results would allow me to add the city with that ID?

Any pointer is appreciated!
Thanks,
Mauro.