One group_listings row for a DUPLICATED group, resolving both the new group and the cloned listing by the slug_index each was just inserted with, so the whole clone (group + listings + memberships) runs as one batch — one round-trip, atomic, and clear of the interactive-transaction round-trip guard. Carries the source member's per-package quantity; the flat price override lives in listing_prices and is copied separately (keyed to the new group).