I agree that you definitely have to be careful with the amounts of both carrots &/or parsnips you add to soups &/or stews.
Both are "sweet" vegetables, & too many (especially parsnips) can add a cloying sugar-like sweetness to any type of soup or stew - whether meat or poultry. In fact, while I do enjoy parsnips as a vegetable on its own, I no longer add them to soups or stews because of the sweetness factor. I don't care much for sweet things - am definitely more a "savory/hot spicy" lover - so parsnips taste almost like candy to me.
As far as correcting the sweetness afterwards, you can try to spice things up a bit (if you like that sort of thing), with more herbs, freshly ground pepper or hot pepper sauce, salt or salt blends, etc. But you definitely have to taste frequently as you go because it's just as easy to make things worse than they were before - lol!!