This will have to be two, possibly three award tickets. However, I suggest put as many flights as you can (up to 8 max that DL can price out) on one PNR, as sometimes DL will price things out in a better and more favourable way than you could even think of (e.g. it may have the destination be your stopover and then you go to stopover and back through destination return (backtracking), and/or only count one shortest/lowest mileage flight as a separate award, or something else like that, that actually will result in less miles than a "logical" pricing should/would).