Custom Graph Definitions

Greetings,

I'm struggling to find clear instruction on how to create some custom graphs.

Scenario: I have a device that I want to aggregate the interface throughput across multiple links.

Specs: Zenoss 5.0.8 on CentOS7

Question: Would I create this custom graph in the Monitoring Template or in the Graph Report/Multi-Graph Report section

Attempt 1: In the Monitoring Template, I created 4 data points, one for InHCOctets on each interface. In the Graph Definitions, I cannot figure out the syntax on using DEF, CDEF, and LINE to achieve my goal of adding them all together. The documentation just links to Tobias' page which is great if you're working on a blank canvas but doesn't help me with the Zenoss specific entries. (specifically 'RRD File') This brings me to Attempt 2.

Attempt 2: In the Multi-Graph Report, there is the Graph Custom Definition section which could provide exactly what I need. I'm stuck when creating the DEF statement since I do not know the full path to use (RRD files are gone in 5) to specify the different interfaces (in years past I could have used something similar to $zenhome/devices/router.domain.local/os/interfaces/eth1_0/ifHCInOctets_ifHCInOctets.rrd.

I've not found a comprehensive guide on how to use the custom graph points and custom graph definitions for any version of Zenoss. Any help the community could provide would be greatly appreciated.

Thank you

Sapofeo