Shoot. This never showed up in my G2G feed; didn't see it until I browsed entries tagged "DNA."
Regardless...Harry, it's sorta impossible to say whether the GEDmatch Tier 1 tools would or wouldn't help. Sounds like you have the kit number for the person you're helping and for a 2nd cousin of that person. Only if you feel comfortable doing so, you're welcome to send me the two kit numbers via a private message from my profile, and I can do a triangulation run plus a matching segment search on the most interesting results of that run. They will be two relatively large, but not massive, Excel spreadsheets comin' back atcha if that's okay. Up to you; if nothing else it may help you decide if you want to subscribe to Tier 1 for a while to play around there yourself.
A caveat: as database migration continues at GEDmatch to merge the original data ("Origin") with Genesis, I've found it can be difficult and sometimes inconclusive if working with one set of results from 23andMe or Living DNA in Genesis, and one set of results from AncestryDNA, FTDNA, or MyHeritage. I'm not completely certain why, but enough anomalies--albeit minor--have been appearing during this transition period that I can't explain why some things end up reporting out as they do. (Queue Twilight Zone them music and a Rod Serling introduction...)
Just to say that if both kits are from the same micro-array chipset, I won't have to explain to you why I can't explain some of the small oddities in report differences.