I have already looked here and it still hasn't given me a definitive answer. It looks to me as if Andersen is a frozen patronym, with Bach as the slægtsnavn, and then from this generation upwards (Jacob & siblings and upwards), Andersen/Andersdatter is a true patronym, but I am still confused as to what I put where. Does the patronym go in LNAB, or the slægtsnavn? From what I read of the guidelines, it talked about one or the other, but not both.
Number 2: "Last Name at Birth and Current Last Name fields will be reserved for slægtsnavn and patronymic names" suggests that Bach would be the LNAB and Andersen/Andersdatter as the CLN, but I want to be sure before I create the profile.