Custom Post Type and Taxonomy Combinations

Not sure exactly how to describe this so I will just give an example. I have a list of locations (custom post type), each of which has a page on my site. I also have a list of vendors (custom post type), each of which has a page on my site.

On the location page, it lists vendors that appear at that location. On the vendor page, it lists the locations where they appear. Right now these are set up as custom taxonomies but there is no relationship between the two. So, for example, if I update that Vendor A is now at Location B on the Vendor A post, I also have to go to the Location B post and update that it has Vendor A.

This seemed reasonable when I first coded it but it has now become unwieldy to add and keep up.

The crux of my question is this: Is there any simple way to store this information in the same spot so that I would only have to update it in one location, and both pages would update?

I am a competent front end coder but when it comes to back end and databases I am a bit over my head.

TIA