If I understood your question correctly, there is a change in an already validated manufacturing process, and needs to be revalidated.
This re-validation, must be done as prospective validation, which means that PV lots cannot be releasede until the validation is completed and approved. If there is an actual rationale for Concurrent validation, then that must be justified in the change control and meet specific requirements for this approach.
A quick description betweem prospective, concurrent and retrospective validation approaches can be seen here: Process Validation
You can read more about requirements for process validation approach in FDA’s guidance for industry: Process Validation and EU GMP’s Annex 15 Qualification and Validation