Place the chicken, butter, soup and onion in a crockpot and fill with water to cover. Cover and turn heat setting to high. Cook for 5 to 6 hours or until chicken is cooked through and no longer pink inside. Approximately 30 minutes before serving, tear biscuit dough into separate pieces (biscuits) and place in soup mixture in crockpot. The biscuits will turn into your dumplings. Test readiness of dumplings by cutting one in half; if its center is cooked, the dumplings are ready to eat.