It does appear that all QF and BA codeshares are allowed on this fare, along with IB and AY within Europe. There must be an MPM or sector limit, otherwise you could do some long routings within the stopover limit. For example you could stay in orbit within the UK for a week without having a stopover, just fly within 24 hours on routings like LHR-MAN-EDI-LGW (routes having frequent service). Even without such gyrations it is easy to construct some very useful routings. An interesting sidelight to this fare is that QF and BA greatly expanded their codeshares in North America on AA flights, and some of these new codeshares made little sense except they serve to connect QF and BA metal endpoints (like HNL to YYZ). So the inclusion of codeshares would seem to be a marketing plan and not accidental. Too bad that there isn't a J version of this fare offered, in some ways it is better than OWE.