Pour the sauerkraut into a slow cooker with one can of the chicken broth and the caraway seeds. Cover, and cook on Low for 2 hours.
Pour the remaining cans of chicken broth into a large pot, and bring to a rapid boil.
In another saucepan, bring water, milk and margarine to a boil. Mix in instant potato flaked until well blended, remove from heat, and stir in the eggs, baking powder, and enough flour so that the dough is firm but not sticky.
Pour the remaining cans of chicken broth into a large pot, and bring to a rapid boil. Pinch off pieces of the potato dough, and roll them into long thin dumplings (like pigtails). Drop the tails into the boiling chicken broth, and cook for 15 to 20 minutes.
Strain the dumplings from the broth, and add them to the sauerkraut in the slow cooker. Season with salt and pepper.