I didn't realize that "natural" daughter implied out of wedlock. Nowadays, natural v. adopted v. step daughter would be how I would see distinctions, natural covering anything from - the father could have been divorced, widowed, or other, but didn't exclude him being married to the mother at the time of conception. The child from there might have been adopted by someone else (have no idea why of course, but thought it a possibility), etc., which was the reason for the term "natural".