Current Cloud Director versions do not have the capability to switch a Provider VDC's secondary resource pool to primary via UI or API.
The recommended option to address this scenario is to merge the Provider VDCs.
Create a new Provider VDC backed by the NEW resource pool.
Merge the NEW Provider VDC to the existing Provider VDC by following the documentation. Step 3 refers to the new and Step 4 refers to the legacy Provider VDCs in the documentation.
Disable the legacy resource pool.
Migrate the VMs from the legacy to the new resource pool.
Remove the legacy resource pool.
Note: