Beef Marrow Bones

Based on Joan Nathan's cooking show (Jewish Cooking in America [archive.org])
6 lbs. beef short ribs
2 lbs. carrots, sliced
1 onion, chopped
4 beef marrow bones (more than original recipe)
10 juniper berries (not in original recipe)
dried thyme and parsley
1/4 c. water

Into the oven at 200 for about 6 hours so far...looking good. You can cut the meat with a wooden spoon.
But next time I would like a little more substance. Does anyone think celeriac might work here? Will it absorb some water and add a starchy quality? I haven't tried celeriac yet; each time I think of it, they don't have any at the market. Anyway, here is the basic recipe.

By Stacie Tolen. Posted to the PaleoRecipe Mailing List, Nov. 2000