Unable to generate person number manually while creating user

Summary: Raising this SR in reference to 4-0000383108, where the requirement is to generate person number manually while creating a new user in order to view the Subscriptions after assigning the role of 'Subscription Specialist' to that user but we're unable to generate person number manually while creating user from 'Manage Users'. We were able to achieve this by following 'Hire an Employee' approach but as it is a part of HCM and the client is not using HCM module, will this be the correct approach to follow?
Could you please provide the detailed process from Subscription Management end to meet the above requirement.