Erm, so sorry. Maybe I should explain with my current scenario and why I need it.
Simply, I am a web hosting reseller and I would like to give my clients a custom nameserver say ns1/ns2.lyniq.com instead of ns1/ns2.reseller.com just to hide the web hosting company from my clients. I choose to use DNS Made Easy because I wish to have more control over my main domain, lyniq.com. I believe dns propagation would also be much much faster. Anyways, I have created lyniq.com using the Managed DNS service provided by DNS Made Easy and followed the Vanity DNS tutorial creating ns1/ns2.lyniq.com.
Let's say I've created an account with the domain duly.com.sg at company A and they provided me with dns1/dns2.companya.com. Since I don't have access to the domain (duly.com.sg), I'll have to let my client know that they have to update duly.com.sg nameservers to dns1/dns2.companya.com right? But I wish to use ns1/ns2.lyniq.com instead, how should I proceed? I know I would have to create duly.com.sg under the Managed DNS section and follow steps 6 and 7 of the Vanity DNS tutorial right? Then add in the records pointing to the server duly.com.sg is hosted on. It is fine since I'd have to just add dns records slowly then just leave it to work. But there comes another problem.
If my client decides to add a subdomain using the control panel software provided (e.g. cPanel) by the host, the records would be automatically be added to dns1/dns2.companya.com. The subdomain would never work if I do not add the record using the Managed DNS section right? Since it's now utilising ns1/ns2.lyniq.com which are essentially DNS Made Easy's nameservers. I was wondering if there's a way to automatically match the dns records of duly.com.sg on dns1/dns2.companya.com to the records under the ns1/ns2.lyniq.com nameservers? So I prolly wouldn't have to even add in any records but just create a new domain under the Managed DNS section. Like what you asked, this means I'd be using the DNS Mady Easy's nameservers.
A second option I thought is to utilise dns1/dns2.companya.com nameservers instead but how do I hide it so that I could give others ns3/ns4.lyniq.com as their domain's nameservers but it's actually utilising dns1/dns2.companya.com. This way all I have to do is to point ns3/ns4.lyniq.com to dns1/dns2.companya.com and need to worry about adding any records.
I hope it is clearer now.