You'll need the whole bag, even if you’re making a smaller batch.
Wine yeast is only one ingredient in your Brewsy bag. The rest of your Brewsy bag is chock-full of yeast nutrient, yeast energizer, clarifying agents, malolactic culture, and ingredients that will make your wine less acidic and give it a rounder, smoother mouthfeel.
Every batch of Brewsy needs a full dose of all these ingredients to be successful. If you split the bag up into two containers, it won't work properly. With a full Brewsy bag, you can ensure that each batch has 100% of every ingredient it needs to be awesome.
If you wanna stretch your Brewsy bags further, you can combine two bottles of juice into one big container. If you've got two 64oz juice bottles, you can pour them both into a gallon jug.