Change of subject for a sec.
RE the names of Constance's hubbies, as attested on WDW attic wedding certifs and in CM training literature:
The Marquis de Doom
Most of the discussion of these has centered on whether George Hightower, Constance's fifth husband, has any connection with the Harrison Hightower III of Tokyo's Tower of Terror. The best answer IMO is, "Probably not." The chronology is wrong, so even at best all you'd really get out of this is that they're relatives. Ho hum. And why form a link to the Tokyo TOT, of all things? More likely it's just a bit of whimsy, an Imagineering tease. If so, "Frank Banks" could be a whimsical nod to Mary Poppins. The Marquis' name is self-evidently a macabre joke (and not particularly subtle, IMO). Reggie Caine...? I haven't a clue.
Now for Ambrose Harper.
I haven't heard anyone connect this name with the building on TSI, "Harper's Mill." Davelandweb has recently posted a handsome 1971 shot of Harper's Mill, back when it was WHERE IT BELONGS, at the tip of the island, now dominated by the "Lafitte's Tavern" stage area. The Mill was relocated around the corner and has turned into Will Turner's blacksmith shop, but to purists it will always be Harper's Mill. Any connection to Connie's first husband? Tease, tease...