Control panel extension: How to add additional field to relationship fields/selections? Which hooks to use, is there a barebone extension avail?

Hey guys,

we are using categories to differentiate entries by language, so our client currently maintains 2 language versions by specifying a category. When assigning existing entries via relationships the control panel only displays the actual entry title, but we need to add the category field to the output/display, too, so our client is able to differentiate entries with the same title by the language.

I wrote a simple extension versions ago and now looked into developing an extension again under v4.x. I think these 3 hooks are maybe those I’d need to look it: relationships_query, relationships_query_result and/or relationships_modify_rows?

On a side note, I cannot seem to find a simple barebone/skeleton/template extension in the docs? Is there something like that available someplace else?

Thanks: Lars