AFAIK you cannot create custom reports in vCOPS. In 5.6 release notes there was something like
Custom Reports (Experimental)
This release introduces an experimental feature for configuring user-defined and pre-defined custom reports.
But never saw it in 5.7 release. may be its possible that way by using the XML-based reporting feature to generate capacity optimization reports at the custom group level, and to run custom reports that contain performance and operational data.
But that is it.