Peplink Balance update noip.com Round Robin record with label

I’m trying to update a round-robin record in noip .com with a label, so that WAN1 and WAN2 connections can be DNS load balanced for incoming traffic.

noip .com supports labeled records, so I can make sure wan1 only updates the record matching wan1, and wan2 only updates wan2 - but I can’t for the life of me figure out what syntax, if any, will work to enter in the “Hosts” section of the WAN configuration page on my Balance One Core.

I can update the regular DDNS entries, but the suggested syntax of “something.ddns.net@label1” doesn’t work because the Balance One doesn’t like the @ symbol.

Is there some way I can achieve this? The obvious one – setting up a CNAME that points to multiple hostnames – turns out to be not legal DNS setup…