My domain: mydomain.net

I'm having a reseller package with Dathorn.com for above domain with 2 nameserver:
ns1.mydomain.net xxx.xxx.xxx.xx1
ns2.mydomain.net xxx.xxx.xxx.xx2

I signed up a VPS with Servint for above domain too. In WHM I do as follow:
Create my hostname: secure.mydomain.net
Create 2 nameserver:
ns3.mydomain.net xxx.xxx.xxx.xx3 (first IP from Servint)
ns3.mydomain.net xxx.xxx.xxx.xx4 (second IP form Servint)

Am I correct with above settings? Is there any conflict?
When I create new account for my client on VPS, is it correct to inform them to change their nameserver to: ns3.mydomain.net and ns4.mydomain.net?

Note: I want to keep my reseller account at Dathorn.com for current clients, that why I set as above.

Thanks,

cPanel.net Support Ticket Number: