Is it possible to combine DNS name servers?

DNS records are a hierarchy. Anything at the same level (v1.example.com, v2.example.com, etc) will all be resolved by the NS records set for that level (example.com)

You can have different nameservers for different levels / subdomains if you are so inclined, for example (example.com at godaddy, subdomain1.example.com network solutions, subdomain2.example.com dns made easy).

This is called zone delegation.