CSP with Multi-Tenant Daas would like to re-assign some licenses to one of their Sub tenants. In this case, the sub-tenant has Single Tenant licenses which have entered Grace Period.
In this case, the sub tenant is standalone Single Tenant so CSP cannot reallocate their Multitenant licenses.
Please advise customer to reach out to their ATS/Account Team to request a License Split+Transfer
In the case where customer would like to allocate the licenses themselves, they need to add a new customer to their Multi Tenant Service as per the docs -