I've got a number of grapes this year and wanted to try my hand at some homemade wine. I don't believe i'll have enough for a 5 gallon batch, however all i have is 5 gallon equipment. If i need to top it off, what's the best thing to use? Can I just use something like Welch's grape juice? Table grapes from the grocery store? If I can use grape juice, would that be added to the must, prior to pitching the yeast?