Polycom IP 650 with Sidecar- how to set additional attendant lines?

The OSS Endpoint Manager window allows me to set up to 10 Attendant lines, but I have a sidecar and want to configure the rest. But I’m not sure where to make the changes to add the additional files. I tried using all of the .cfg links at the top of the Template Editor window, but none show the actual attendant lines I added. I can edit the file manually, but I’m not sure which file to edit.