This is a follow up to a discussion in the English Wikipedia:
https://en.wikipedia.org/w/index.php?title=Wikipedia:Help_desk&oldid=829453955#Editing_interwiki_links_in_Wikidata

The current error about adding a sitelink that is already linked from another item says "The link $1 is already used by item $2. You may remove it from $2 if it does not belong there or merge the items if they are about the exact same topic."

The suggestion to merge the items is not linked directly from the error, and the person who sees the error has to look for merge instructions.

It would be nice to link directly from the error message to the merge instructions or the actual merging form.