So maybe OneWorld is excluded entirely?
Well, better to find out NOW than to be standing there to no avail, having to find other options at the last moment!
I have contacted the service, and Hertz (the new operator) advises to contact Lufthansa - yet refuses to supply any contact information other than using the lufthansa website contact (which, in turn, only provides contact for check-in, lost luggage, complaints and so on).