It is correct to show proper names ending in -s being possessive in two ways. Most common and slightly more correct would be to add an apostrophe -s (i.e. Frances's) however it is still correct to write it as just the apostrophe without the additional -s (i.e. Frances'). To indicates multiple people named Frances, one would add the typical -es ending (i.e. Franceses).
The plural of name is names.
If your first name was Jayne, then the plural would be JaynesIf your last name was Smith, then the plural would be Smiths
The plural form for the name Edmonds is the Edmondses.
The plural for for the name Usie is Usies.
The plural form for the name Marcus is Marcuses.
The correct plural spelling of the first name Frances is Franceses.
The plural form of France is "Frances."
Frances Sage's birth name is Frances Satz.
Frances Bergen's birth name is Frances Westerman.
Frances Bay's birth name is Frances Goffman.
Frances Faye's birth name is Cohen, Frances.
Frances Farwell's birth name is Frances Gurewitz.
Frances Drake's birth name is Dean, Frances.
Frances Foster's birth name is Frances Brown.
Frances Waverly's birth name is Frances Krause.
Frances Horwich's birth name is Frances Rappaport.
Frances Hatton's birth name is Roberts, Frances.