I have found this Sansouci + Valley marriage, perhaps this is the couple you seek?The dates between both of our data is a few years off, perhaps it may still aid in your search. I found the notes regarding this marriage to be most interesting! The surname of Sansouci has also been spelled Sansoucy or Sansoucie.
Sincerely, Joni VALLEY Stockinger Huntington Beach, CA
Joseph Albert Valle b: 01 May 1877 in Old Mines, Washington, Missouri. Parents: Theodore Valle b. Dec. 1849 & Marie Therese Courtois. .+Mary Therese Sansouci b: Bef. 1883 m: 12 Sep 1899 in Old Mines, Washington, Missouri. Parents: Charles Sansoucy & Ellen Courtois.
[Here's some information from copies of old church records, just as it is written.. Priests' notes dated May 17, 1899Parish of St. Stephens, Indian Creek, Monroe County Missouri. [Old Mines Missouri]"Pronounce Marriage Albert Valle & Teresa Sancoci. . . .Marriage licenses dont tell your affairs to every one come to Priest. . Squire marriages will not be patched up by me. I'll resign the parish first."]