You are correct.
FFF plugin doesn't have a way to identify a cover you have set manually for an anthology vs one that was found.
As mentioned in the
wiki page, you could use a
force_cover_image for the first book story URL. But you'll need to save the cover somewhere and add that setting.
If you use a specific anthology GC set from
generate_cover_settings (like I do), you also need to adjust it to
not execute when the cover type is
force:
Code:
add_to_generate_cover_settings:
${anthology} ${cover_image}=>^true [^f].*$=>FFDL