Back in those days, 1961, the tax rate was 91%, and more if added state income taxes. Obama Sr. was being sponsored by people like Harry Belafonte and Sidney Poiter behind the Foundation. Sooo, a plane trip would have been deductible and only cost the rich supporters maybe 2 cents on the dollar. I did a Internet Article on this. This does not mean this is what happened, it just means it would be financially possible in opposition to you saying it is not financially feasible.
Harry Belafonte and Sidney Poitier contributed to the program for educational expenses. Are you suggesting that they (or others like them) would have made a separate contribution so they could send the pregnant wife of a student to Africa and back? Why would they do that, instead of sponsoring an additional student?
In 1961 Harry Bellafonte was known as an ultra-radical socialist propagandist. He had just completed his Island in the Sun movie that exploited racial issues with massive hyperbole.
These were the kind of people the Dunhams were known to associate with.