Join Isilon to multiple AD domains

Question: How to join Isilon cluster to multiple domains.

We have an isilon cluster which is joined to production domain AD1 and have 3 DNS servers (dnsserver1,2,3) listed for the domain in isilon network configuration GUI . There is a new requirement of joining the same cluster to DEV domain AD2 which has its own dns servers dnsserver3.4. There is no trust between the AD1 and AD2. how do I configure isilon to multiple AD domains. There is no option in GUi to add second set of DNS servers and specify a DNS serach list. In GUi, under access management, active directory, there is an option of configuring additional active directory providers. But not sure without specifying DNS servers for DEV domain, how will it join to AD2 domain. Any idea guys? We are on 7.0.2.1 code

thanks in advance.