Modify / Delete:  No (no support, no update capability)

Existing tier and tier-group definitions may not be adjusted or deleted.  

Due to Esri’s technical requirements, deletion is not possible in the one-time-setup database.  

Justification:  

•The entire network is structured based on the tier definition. Modification or deletion of a tier can corrupt the correct functioning of the defined utility network and the configured applications.

Create: adding a new tier and/or tier group is permitted. The name must start with the prefix “CUS_”.

Observe Esri’s general conditions!  See Esri Help (disable network topology, feature classes should not contain data).