Can a custom role with required privileges perform the change assignment transaction

Without any employee/cwr abstract role can a custom role with required privileges perform the change assignment transaction?

Requirement is to have a standalone role created for a certain number of users without having a person record created in the system for those user; users with this role should be able to perform Change assignment task without having a person record and employee or any other abstract role. Human Resource Specialist delivered role can perform the Change Assignment transaction without any person record/abstract role, but we can not assign this role as this will open a lot of access. With the standalone role we created, we can open the change assignment task but can not submit the transaction.