I have looked through LDS film 1298739, and there are St-Louis's in there.
First, I think (not sure)that I have found my g grandmother. There is record of a birth of a Mary Anne in 1842 to Louis St.Louis and Susan Lezare. I am not sure because my g grandmother was Mary Jane (Marie Jeanne) or sometimes just Jeanne in all other records. However, there are other discrepancies in these records, so I think this is possibly the right person.
There is also a record of their marrige.
In 1844, they had a son, John (second name either Henry or Harvey).
In 1845, a daughter Mary was born to Joseph St. Louis and Marie Brissette.
In 1858, there is a marriage of Joanna St. Louis (could it be my g grandmother? Maybe).
In 1863 there is a death recorded for a St. Louis. Unlike other death entries, this one has no age or other notes. The first name is about 6 characters, and appears to start with E. I can't make it out.
Then in 1854- 1855, there are 4 St Louis children buried, all under 3 years of age.
I also found the records from the French community in Minnesota; although the church burned, some of the records were preserved. These records are in French. Among them:
In 1878, my g grandfather and his wife (Jeanne St. Louis) had a son baptized. The sponsors were Joseph St. Louis and Marie Brissette. Apparently her brother (?) came with her to Minnesota.
Also in 1878, a son, Joseph Alexander was born to Joseph St. Louis and his wife, name illegible, but it is not Brissette. The godparents were John White and Christine Lewis.
What is interesting to me is that these are the first non French names in the record. I know that John White was really John Leblanc; he anglicized his name. I learned that from his grandaughter. I am speculating that Christine Lewis is really Christine St. Louis, and that she also has anglicized her name. Perhaps that is why there are no St. Louis' in that part of Minnesota today.
Finaly, I spotted this on the Gervais GenForum site.
" If you look up Mormon reel no. 1703968, you will find that a marriage register dated 1836-1839, 174 pages, kept by missionary Charles DeBellefeuille, and which is held in Pembroke, Ontario. For year 1837, we find that he performed 190 baptisms and 25 marriages. Among which we find: ... 12) 16 août 1837 (La Passe) : Hyacinthe St-Louis dit Filiatro et Scholastique Martel ... "