They'll be a OW member in the next 1-2 years, but not yet unfortunately. Until that happens, you can't used them on DONEx. You can however used them on DGLOB34, but then you're limited to 34k miles in total which may or may not be possible based on how many intentional long-er haul segments you have than is actually necessary to complete your itinerary. Just for example, something intentionally criss-crossing continents like xxx-JFK-SEA-DOH-DUB-DOH-MAD-DOH-xxx isn't likely to work on a DGLOB34, that needs to be done on a DONEx where mileage doesn't matter.

But DGLOB34 and DONE4 are typically nearly the same price, so if you have an itinerary that's more efficiently routed then you can use FJ.