Best way to merge two databases with large overlaps?

[ThiloteE]

Best idea so far about merging two databases with large overlaps:

@impracticaldogg

The best idea I have is to import the references from the old Zotero set to a new JabRef database, generate a fresh set of BibTex keys based on my existing template, and then merge the two databases. The difference between the original and merged JabRef databases should only be the new imported records plus the tens of records that I edited manually (and likely have different BibTex keys).