How can I make a Hyper-V host, in a perimeter network, also a Library server in VMM 2012R2?

I am unable to add a Hyper-V host in the perimeter network also as a Library server in SCVMM 2012R2. The host is in the same domain. When I try to add it as a Library server it says 

Error 409: Server is already associated with a Different VMM server. .....Recommended action is to reinstall VMM agent and try again.

Although the host is added to this VMM server. And adding it as a Library server first doesn't help either. Is there any powershell command to achieve this or is there any constrained delegation required to achieve this ?

Ayan Mullick Principal Infrastructure Engineer. British Petroleum.