I am trying to use an intermediary post type in other relationsships. Here is the scenario:
Events<<Instances>>Locations (m:m relationship with intermediary post type)
Now, I would like to
- add taxonomies to "instances"
- use "instances" in another relationship
Apparently this is restricted for intermediary posts. Why is that the case? Is there a way to allow it or a workaround?
Thanks for the help!
You are right that intermediate posts cannot be used in other relationships, it is a core limitation, and there isn't any kind of workaround that can facilitate it.
It is also the case that taxonomies are restricted (as can be seen in the screenshot).
When the API was designed the intermediate post type was envisaged to be used exclusively as a container for relationship custom fields.
If you wanted to use them more like typical custom post types, you could try replacing your M2M relationship with two one2M relationships, where the "one" in each relationship was the same post type that served as the intermediary but which could also be used as an intermediate post type of some other relationship (and which could also have taxonomies assigned).