Suggest Treatment For Baby Born With A Small Stomach

My daughter has a didelphic uterus and just had a baby three weeks ago. Some complications during delivery, baby is ok but born with a dangerously small stomach , per high risk doctor. Baby can t hold down breast milk and most formulas, although one was found she can handle. She s not feeding much, just got up to 3 oz. She hasn t gained any weight, weighing 6 lbs. She was born 3 weeks early due to placenta evaporating. What do her stomach issues mean? Will surgery be eventually needed?