one bottle increase the amount of port and sugar proportionately but you don't need to double or treble the spices. I've been mulling the cheapest red I could find in Tescos this week, Marques de Leon (from the label I'm guessing it's an unoaked Spanish red, as you've recommended above - I'm totally ignorant about wine). It's been lovely, but I do add lots of sugar. Much more than your recommended 2 tbspns. Also cinnamon, cloves, a cup of orange juice and a sliced orange. I also make a non-alcoholic version using 1l cranberry juice and 1l apple juice in place of a bottle of wine, only 2 tbspns sugar but orange juice and spices as above. Very useful for drivers and those needing a clear head eg for carol service choristers.