>> If you insist, you could take a gallon out now and refrigerate it
for later
addition. The yeast won't go far in the 'fridge.<<

I realized that I don't even have an airtight container to put in (I'm
going to order some 1 gal jugs). It would have to be a pitcher or
something like that. Also, oak chips have also already been added and
the must is fermenting quite a bit. I took a quick, rough hydrometer
reading tonight and s.g. was down to about 1.075. Would there be any
benefit to adding sugar or even grape juice when the vigorous
fermentation subsides, since I don't have the separated must to add
back?