I know of at least two instances where the woman coming to the US used the surname of her intended or another relative. One of them was my great grandmother's sister, who was either a widow or divorced in 1898, but she used her sister's married name instead of either her own maiden name or married name. Or misunderstood the question, and the person making the ship's list wrote down the wrong answer. You think they would be showing a document to get on the ship, but the fact that I've found two of these means it is possible in other cases, too. Unless you have found Marie Sitka, do consider the idea that Marie Nickmann could be yours.