GSA CTA Team Members vs Sub

Status: Team Lead (prime) on a GSA BPA Task Order with multiple CTA Team Members (co-primes) utilizing their own GSA schedule(s) and multiple subcontractors currently utilizing our GSA schedule. 

Issue: Some of the current task order subcontractors are Team Members (co-primes) at the BPA level, but elected subcontractor status at the task order level during proposal. The Program Manager is now asking if a subcontractor can be changed to a CTA Team Member on this task order (post award). I’ve changed a firm from a CTA TM to a sub due to their GSA schedule expiring and not being renewed, but it was a rare situation.   

Question: Does anyone have guidance or experience with this scenario, or know if any restrictions?