I've started a Parsnip wine. It's been racked off the lees and I reserved 500ml of juice mixture for topping up. its been fermenting steadily for over a eek and there is a good depth of sediment in the bottom of the demijohn. Should I rack now and top up or is it best to wait until fermentation stops. If the latter will it start to ferment again as I will have added more sugar when topped up? Any advise on this one?