Discovery of ifAlias for Moxa Industrial Switches is blank

When discovering Moxa Industrial switches (Moxa-EDS506P, and Moxa-ICS-G7826A), the ifAlias is blank. I believe this is because the MOXA SNMP oid is under enterprises private 1.3.6.1.4.8691.7.(162,199 respectively). 

SNMPv2-SMI::enterprises.8691.7.99.1.1.0 = INTEGER: 26
SNMPv2-SMI::enterprises.8691.7.99.1.2.0 = STRING: "ICS-G7826A-20GSFP-4GTXSFP"
SNMPv2-SMI::enterprises.8691.7.99.1.4.0 = STRING: "V4.5.18 build 18041218"

....

SNMPv2-SMI::enterprises.8691.7.162.1.9.1.1.7.3 = STRING: "CAMERA"
SNMPv2-SMI::enterprises.8691.7.162.1.9.1.1.7.4 = STRING: "BROADBAND"

I would like to map this OID(portName) to the ifAlias field. but unsure where that is code hierarchy as the developing section for ports is still TBD.