Merge tool for records needed

[jenniferward]

ZR editors need a merge tool for records when we spot duplicates. We usually go from MS to print but we might also have to merge print and print.

It can be similar to what we do for the template switch (#1249) where we have a selection screen. Here, fields from Record A (the duplicate) get moved to Record B (the final record) if you click the box. However sometimes there are different "layers" to merging so I don't know the best approach:

• Sometimes we need to move from A to B's holdings (like a previous owner) -- Sometimes B's holdings are new, sometimes they are already present
• Sometimes we need to overwrite B's fields with values from A (240, 245, 650 usually)
• Sometimes we need to move new fields from A to B

I think we can always add:

• Fill out B's 588 based on A's 852$a and 852$c
• We need a new 500 note in B that says "This record was merged with RISM ID no. {001 from A}."

What is feasible? The current situation is we copy and paste from A over to B, which can introduce errors (especially if there are dozens of music incipits involved). If we could automate some of this, it would be an improvement.

[fjorba]

In our provisional merge tool (see #1600) what we do is to add all fields of the bad record that do not already exist into the good one. And then it is easy to delete the unneeded ones. For the authority records, of course, 1XX tags are turned into 4XX.