It is obvious from this thread that Howey is a name in its own right. However, I note that none of the names discussed slope off to Howie or Huie. A thought for your particular query.

Flora MacDonald was born in Benbecula and her family had lands in South Uist where her brother built a house in 1845/6. Both were MacDonald of Clanranald territory. I have never run across the Howie name or variants but Buidh usually written Bowie or Buie, was a common name in the district of South Uist where Flora's family is recorded. There is some debate whether it simply means Yellow (haired) or shows that the family came from Bute. When aspirated in Gaelic to indicate the possssive, as in mac Bhuidh, son of Buidh, Bhuidh would sound pretty well like Huie. Might the clerk who wrote down the name from someone who was not literate in English, thus have changed the name from Buidh/Buie/Bowie to Huie/Howie?