Sorry, I'm a little confused. Can you tell one again which Xrefs you can see in drawing D in a situation described above?

>>>>'m not sure how to check the dwg version of each
When you open drawing in AutoCAD, you can see its version at the command line, for example:
"Opening an AutoCAD 2018 format file.
Regenerating model.
AutoCAD menu utilities loaded.
AutoCAD menu utilities loaded.
Command:"