Originally Posted by
ISTFlyer
Unfortunately, TK doesn't match oneworld Sapphire to Elite so you were correctly rejected by them.
While, the benefits of OWS and *G might be similar, TK is the one to set the T&C of this program and they could decide whatever to do.
As far as I know, they did match at least one Finnair Gold here ( oneworld Sapphire ) which was back before COVID but other than that I have not heard any OWS being successfully matched to Turkish Miles&Smiles.
Except they did exactly this for me earlier last year - just before a TK flight I did BKK-LHR in April 2022 - from Cathay Gold (OneWorld Sapphire) to Miles&Smiles Elite so it's not a clear-cut rule. The OP may have been referencing my posts in this thread on the subject.