Provision of second sip server on an account.

Using the M7 configuration file format I'm trying to work out how to set the second sip server for an account.
Unfortunately this doesn't appear to be documented and its not in any of the sample files.
Exporting the configuration doesn't help either as the export file contains the old M1/M2 file format.

So firstly what are the required settings?

Secondly can you please update the provisioning manual with the M7 settings. Its extremely frustrating trying to work out all the settings!!!

Thanks in advance.
Brett