Change of Job Role

I was granted two undefined Certificates of Sponsorship (CoS) last year for the roles of office manager and Electrician Both positions have since been filled by overseas workers using defined CoS. As a result, I now have two unused undefined CoS that were initially allocated for these roles.

I would like to use an undefined CoS for a new role, Energy Assessor, which falls under a different SOC code 3541. Could you please confirm whether I can use one of the existing undefined CoS for this position, or if I need to request a separate undefined CoS specifically for this job role?