I believe Pan Am and United were the main air carriers from Hawaii to the mainland in 1961, thus contacting a retired employee might be of some use. Currently each airline has their own policy on newborns flying some 7 days some with doctors note and/or due date etc...
I did find a cargo ship that took some passengers to Kenya in the 60’s but could find no more info and misplaced the name.
They claim there was a rule prior to the 70s. However, I want to see independent verification of anything coming from WND.
I find it very curious that they just now ..all of a sudden...found the info from the Polk directory about Dunhams living at that address.....after they had hired a PI last year.