I recently had to solve this exact problem in SQL Server — copying rows within the same tables (A → A, B → B) and making sure all foreign keys point to the newly inserted rows.

To handle it, I built a reusable migration tool that:

• Recursively copies related records based on FK dependencies

• Remaps all FK references to the new rows

• Supports filters, value overrides, and dry-run mode

If anyone's interested in trying it out or giving feedback, I’d be happy to share it privately.