Hosting a subdomain, keeping DNS and www intact

Hello,
totally newbie here, I have a question about hosting only a subdomain here.
I own a domain, say example.com, which DNS is hosted somewhere and main site is hosted elsewhere.

To host a mirror of current web here for testing, I am trying to set-up dh.example.com and yet to succeed.

First, tried Manage Domains->Add New Domain/Sub-Domain and to create dh.example.com and resulted 'Can't add domain: you don't have permission to add to example.com.'

OK, so did the same thing for the root domain example.com and succeeded. But when I look into the DNS records:
Non-editable DreamHost DNS records for example.com:
Record (example.com zone) Type Value
A 67.xxx.xxx.xxx
NS ns1.dreamhost.com.
NS ns2.dreamhost.com.
NS ns3.dreamhost.com.
ftp A 67.xxx.xx.xxx
www A 67.xxx.xx.xxx

No, this is not acceptable. I'm not going to change the addresses of current ftp and www.
Since I'm not changing SOA and NS records of current registrar and DNS, I know these records do not affect most of the internet, but I wonder about the outcome when digging the hostname inside Dreamhost.

So, the questions are:
1. What is the normal way to add a sub-domain in such a situation?
2. If the process above is OK, are there any side-effects by the bogus records hosted at ns*.dreamhost.com?

Thank you all in advance.
Regards,
kazua

1) Your approach is the right way to add a subdomain. I've not had to use such an approach, but have you tried adding a subdomain, and then removing the domain? Perhaps that will delete the unwanted A records.

2) The only side effects of the NS and A records is that you won't be able to reach your externally hosted domain from within DreamHost. However, if you can delete the above mentioned A records, this should no longer be a problem.

-Scott

> and then removing the domain? Perhaps that will delete the unwanted A records.

It worked! Thank you!

After adding 'dh.example.com' and then deleting 'Web Hosting' of 'example.com' produced following output:
NS ns1.dreamhost.com.
NS ns2.dreamhost.com.
NS ns3.dreamhost.com.
dh A 67.***.**.***
ftp.dh A 67.***.**.***
www.dh A 67.***.**.***

This is what I want. Although the procedure doesn't seem to be straight forward enough, I should have noticed.
Well, as another story I have to consider how to work around unexpected IP address changes, using CNAME or zone delegation, I have enought time to think about them. So it's OK for now.

Thank you again for your quick and prompt advice.