veins on the outside of it or just veins that you can see through the skin? do you have pictures? I'm going to tentatively say that if the "veins" are disappearing from the outside it could be absorbing them, which is what you want. do you see blood vessels on the outside of it? pictures would be helpful. I'm not super experienced with hatching and I haven't hatched duck eggs but have had to help chicks hatch before. there is a egg hatching intervention guide on here somewhere that is very helpful, I will see if I can find it. it's good that the membrane isn't dry, you want it to stay moist. if it starts to dry out you could try putting a little bit of coconut oil on it to keep it moist so it doesn't shrink wrap and it can absorb the blood vessels easier. is it still in the egg?