It should be fairly simple:
One can only log Copilot hours, if the aircraft is required to be flown by a crew of two-either by the FOM, or by the company OM.
If it is a single pilot helicopter, you cannot log hours-legally.
Hours donīt mean anything anyways....i have seen Captainīs with 3000 hours not able to fly, and Copilots that only had 500 hours having a perfect hand for the machine....
All it is is a number in your cv, defining whether you qualify for "insurance discount" or OGP standards, or not...