Merging of records with same fingerprint from different readers

The same copy could be described in a record from the STCN as well as the USTC (fictional example). Theoretically, such duplicate records could be recognized by having the same fingerprint.

Jeroen would like to be able to merge such duplicate records. The most complete version should be considered the base, to which fields from the other record are added.

Jeroen can work around the lack of this feature by adding both records to a collection, filtering or sorting the collection by fingerprint, adding a blank record with the same fingerprint and manually copying over all fields from the original records to the blank one. This is, obviously, less convenient than having a merge button. I have not asked how often this situation comes up.

No files, tests, or entry points are named in the issue. Start by tracing how records are selected and edited, then clarify how the most complete record and conflicting fields should be determined. Done means a merge action combines duplicate records with the same fingerprint while preserving the intended fields.

Written by the indexing model from the issue text.