Subdomain of a Subdomain?

Hello, We have a reseller account, where we have a high quantity of domains. For most of the domains, we created a account for it. In some cases, we have to park a subdomain of these domains, to another domain (inside the whm, but a different account). Example: we have a system on panel.ourdomain.com and we park others subdomains to it, like: panel.domain1.com, panel.domain2.com, panel.domain3.com. Our system recognyze the domain, and select the correct "database" to use. The problem is, when this subdomain that we are parking does not have it own "account" with the main domain, it works fine. If there is already a account with that main domain, it shows a error like: "... this domain is already of another user". Is there anyway to park just a subdomain into another subdomain from another account inside the same whm? Thx