It would be useful if the DNS proxy property was copied from the "parent" domain.

• I have example.org with DNS proxy X
• I create sub.example.org
• Foreman defaults to DNS proxy X because of the parent
• I create sub.example.com
• Foreman defaults to none because it can't find a parent

The same can be done for subnets because they are rewritten to in-addr.arpa:

• I have 172.17.0.0/16 (17.172.in-addr.arpa) with DNS proxy Y
• I create 172.172.17.1.0/24 (1.17.172.in-addr.arpa)
• Foreman defaults to DNS proxy Y because of the parent
• I create 192.168.1.0/24
• Foreman defaults to none because it can't find a parent

This would make handling of many subdomains and subnets a lot easier. For me it doesn't have to track sub zones once they are created.