There are TWO (2) Bel Family Lines. They are related, but back in Haute Savoie, France - before the two lines came to New Orleans. I have the pedigree and am working on a gedcom for the Bels. In short, anyone who knows their ancestor is John Hamilton Bel is closely related. Anyone with the Boutte or "Antoine Bel" ancestor is closely related.
Those in the South Louisiana area (New Orleans, Tangipahoe, Lake Charles areas) are all cousins, but to different degrees. Also the Bels that moved to San Antoine, Texas (like Alan Bel who is now living in UK) come from the "John Hamilton" line.
I'm at work right now, so I don't have my files in front of me, but I will elaborate on the two different lines in a future message.