Fetch NS names and glue from both parent and child zones (in some way)
After !1097 (merged), Knot Resolver is properly parent-centric in the resolution.
I recently fixed
iter_pcnamech.rpl in deckard!207 to actually test something and it requires a query to the child zone to discover a NS name/address to pass.
Moreover https://tools.ietf.org/html/draft-ietf-dnsop-ns-revalidation-00#section-3 points in the direction of querying the child zone as well.