Using the VarToy, I'm looking for buddy files for a .NEF file.
For the search I use the variable "{File.BuddyFiles}" (see attachment "VarToy_result.jpg").
As result 7 files are displayed (see attachment "VarToy_result.txt").
As result I would have expected only the 2 files ...Cuxhaven-11.JPG and ...Cuxhaven-11.xmp.
Why are the 5 other files recognized as buddy files of ...Cuxhaven-11.NEF?
The 5 other files are photos with completely different content.
Without knowing your File Relation rule for Buddy files of .NEF, I can only guess. My guess is that you use a wildcard expression in your rule so that all files starting with the same string as the master file are matches for buddies. For example (note the .* in the expression):
^{name}.*\.(jpg|jpeg)$
With this rule, if you have a NEF file xxx_11.NEF, xxx_110.jpg, xxx_111.jpg and so on all start with xxx_11 and are therefore matches.
Show how you have configured your NEF buddy files in Edit > Preferences > File Relations.