You can add more than one subnet to each network using the BOSH Director.
After you deploy VMware Tanzu Operations Manager, you can expand your network with multiple, overlapping availability zones (AZs). You might want to create subnets with overlapping AZs if your current subnet is full and you determine that your network needs expansion.
To add an additional subnet to your network:
Go to the Tanzu Operations Manager Installation Dashboard.
Click the BOSH Director tile.
Click Create Networks.
Click the name of your network to expand the network details.
Click Add Subnet. This action populates a new set of subnet fields. You might need to scroll down to see the fields.
Complete each of the subnet fields. For more information about configuring your subnet, see the Tanzu Operations Manager configuration topic for your IaaS installation.
Click Save.
Return to the Tanzu Operations Manager Installation Dashboard.
Click Review Pending Changes.
Click Apply Changes.