Enologo, in my response above I assumed that you were talking about making a triple batch of one variety. If you are making multiple varieties, you have a choice in separately fermenting and blending (or not) later as Bacci suggested or co-fermentation where you blend all the varietals in a large fermenter and co-ferment them. I have done blending both way and, frankly, I do not see a lot of difference. You may have a more discriminating palate than I. Some examples of co-fermentation that I have done was to mix Zinfandel and Muscat juice and then ferment, mix Sangiovese, Merlot and Cabernet Sauvignon juice and then ferment and to mix Sangiovese and Cabernet Sauvignon (no Merlot) juice and ferment. I have separately fermented Zinfandel and Muscat and blended the finished wine and I have separately fermented Barolo and Brunello and blended the wine. As Bacci says, the possibilities are numerous. Good luck and let us know what you decide to do.