Update: Sutter Home Vineyards just sent information about their Chardonnay
"Sutter Home Chardonnay has only been treated with Bentonite to protect against heat stability issues and tartaric acid and citric acid to adjust natural acidity. Grape juice concentrate is added to provide sweetness."
My thoughts: Bentonite, tartaric acid, citric acid, and (malolactic fermentation as published in Walmart ad for Sutter Home Chardonnay) are additions to what is supposed to be 100% grape juice for sacramental wine.
The grape juice concentrate must be added after fermentation, because any sugar added during fermentation does not result in sweetness because the yeast consumes the sugar and only increases the alcohol content, not the sweetness in the final wine product.