I'm on hold on this profile, waiting for access to add a daughter.
In the meantime, I noticed in the bio that this person was born Pedersen, by Danish/Scandinavian patronymic tradition. Later in life, he changed it to Mortensen, also his father's surname. One sees this pretty often among Scandinavian immigrants to the US.
I have an Icelandic friend who was not allowed to give his son a patronym in the US even though they wanted to; back in the 1990s this was. In Iceland, the phone book is alphabetic by first name - not an easy concept if you're not used to patronymic traditions.
Anyhow, Mr. Mortensen was born Pedersen, later changing it to Mortensen like his father. I suspect that they were required to abandon the patronym upon immigration to the US. But for WikiTree, the LNAB should be Pedersen, no? Then changed to a different one, entered like we enter married last names for women.
I'm pretty sure I'm right on this, am double checking before bothering the profile manager further.