It is interesting that your McElhattonsfirst went to PA.That is where William McElhatton settled in the1740's.We know from his Rev. War army enlistent papers that his son Alexander was born in Derry, Ireland.I have been searching Northern Ireland but so far have notfround any records.
You are right that may Hattons were McElhattons.William'ssons changed the name to McHatton about the time of the Rev. War & except for a few of uswho use MacHatton the name has remained the same.
Wethought that the McHattons living in MA might be descendants from Neil McHattonwho was sent to MA as an indentured sevant in 1685--he fought on the losing side of a war. I guess not.