DNS on Netware Forward specific zone

We run DNS on OES 2 Netware (6.5 sp8).

Our DNS zone is (something like) thistrust.nhs.uk

Forwarders for all unknown zones are configured to NHS.UK name servers and work.

Glue records exist for our Active Directory ad.local zone and sub zones - all working as required.

Now we need to be able to forward requests for a partner zone thattrust.nhs.uk to their own DNS instead of forwarding with all other unknown domains to the nhs.uk DNS servers. I had thought glue records would help but I relise that would break resolving for all other nhs.uk zones :-(

I have read threads here (from a few years ago) that it is possible using bind commands in the named.con file, but that is ignored when Named.nlm can read eDirectory.

We have attempted to put an A record for ns1.thistrust.nhs.uk with the IP address of the server which is actually ns1.thattrust.nhs.uk, created a zone thattrust.nhs.uk with the ns1.thistrust.nhs.uk as NS record but this doesn't resolve host.thattrust.nhs.uk

Using NSLOOKUP to change DNS server (by IP address) to ns1.thattrust.nhs.uk I can resolve host.thattrust.nhs.uk

Is it possible with either the DNS-DHCP console or iManager to configure forwarding for a specific zone to the relevant DNS servers?

Anthony