Rosalind, came across your request. I was married to a Garlotte from Biloxi, Biloxi, MS. The family weren't Creole, however, as you may know by now that there were various spellings of the name Guillotte. I will send you a list now of the different ways I have seen it. The spelling of the name was often due to someone not knowing how to spell the name when the census was taken and would record it from how it sounded to them, Many people back then in that area didn't even know how to read or write. In the much earlier years the name was spelled according to which country was ruling the coastal area. The French spelled it one way and the Spanish another, then came the English version.
Names Grelot (French) Name showed up on the Gulf Coast in Alabama in mid 1700's. Gollot (appeared by the end of the 1700's) Garlotte (seen as early as 1800's) Garlot, Gallot, Gaulet, Guilotte (seen during the mid 1800's) Garlott, Girlot (seen in late 1800's) Gollott, Garlotte (presently seen along the Mississippi Coastal area.)
I've never run across the spelling of Gilyot in the family line I've worked on. In any event, I hope that maybe some of these names might be helpful to you in your quest on your Gilyot line.