Umm:
Joan Wingate Lamb was born in Chicago in 1940, to Deborah (née Bent), a housewife, and Theodore, an architect who died in a plane crash in Portugal in 1943.
American, plane crash, Portugal a neutral state, 1943?
Architect? Possibly, but probably not the reason for that flight.
“In 1943 he left for London to an appointed post as an attache at the American Embassy heading an Office of Civilian Defense commission to report on the effects of bombing on various types of buildings.”
Probably not much bombing in Portugal, so…
This says he was on his way TO London to take up the post, via Portugal (presumably the Azores route). It was February, so the Greenland/Iceland route likely undesirable for non-military flights.
https://www.geni.com/people/Theodore-Ted-Lamb/6000000015807556383
Lisbon was a hotbed of espionage, or at least attempted espionage, during WW2. Ian Fleming was based there for a time:
https://literary007.com/2017/04/13/following-the-money-ian-fleming-and-the-origin-of-casino-royale/