With a melon baller, scoop the watermelon flesh from the shell. Set the watermelon balls aside. Scrape out and discard any remaining flesh. Notch the rim of 1 watermelon shell half with a decorative zigzag and refrigerate the shell. Discard the other half.
To make the dressing: Combine the lime juice, orange juice and 2 tablespoons of the honey in a large bowl. Add to the dressing the watermelon balls, blueberries and kiwis. Toss the fruit well, then refrigerate the salad for 1 hour.
To prepare the sauce, whisk together the yogurt, remaining 2 tablespoons of honey and liqueur. Refrigerate the sauce.
At serving time, set the watermelon shell on a large platter. Toss the salad once more to coat the fruit with the dressing, then spoon the fruit into the watermelon shell. Serve the chilled sauce in a separate bowl. Serves 6.
