I will bounce this information off you to see if perhaps you can varify or provide corrective information. Marguerite (Morrissette) Cheffer, at her marriage was minor dau of Francois (Nov 14, 1794- Nov 30, 1869)and Marguerite (Boucher) Morrissette borne Apr 27, 1798), Married July 03,1826 in Louiseville,Maskinonge, P.Q. One of her siblings was Tousaint, who was my branch.

When the family moved to Papineau/St Anne, Iroquois Co., Illinois the year before Marguerite's marriage, there were 10 children listed in the family. I have since discovered two new Morrissette families who came into the area approximately the same time one has interaction with the family in its records, the other does not. Seems logical that these may have been previously married siblings, or close relatives. Below is the research information source and my assumptions: Can you clarify?
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There are two more families who are possibly tied to Francois and Marguerite Morrissette's family.
Source: Fr Chiniquy's ledger, St. Anne's Catholic Church Records.
1866 baptims of Achille Morissette, born Aug 25, to Zephirin & Delima Morissette (It is believed Delima and Celina are the same person)
1865 Marriage of Zephirin Morrissette and Celina Ducharme
1869 Baptism of Samuel Morissette, Borne Mar 11, 1869 to Zephirin and Celina Morrissette
1869-1880 burial of Zephirin Morrissette
1871 Marriage of Cyrille Adams and Celina Morrissette.

Note: Also from Fr Chiniquy's ledger.
Nov. 7, 1865, Zephirin Morissette and Celina Ducharme were married at the Second Presbyterian Church in St. Anne by Pasteur H.E.Lippert
Between 1869 and 1880 Zephirin died and as buried at the Second Prespbyterian Church, St. Anne.

Information provided by Carol Anne Chiniquay, Source 2nd Presbyterian Chruch, St Anne , IL:
Nov 7, 1865, Zephirin Morisette (Rom. Cath.) and Celina Ducharme, member of this parish.
Nov 18, 1866, Baptism, Archille Theodore Morisette, Son of Zephirin & Delina Morisette, Born Aug 25, (It is believed Delina and Celina are the same person.)
May 23, 1869, Samual Morissette, son of Zephirin and his spouse Celina Ducharme, Born March 11, 1969
It is possible Zephirin's interfaith marriage resulted in shunning by the family.

Probate Document dated 1881 concerning he guadianship of Achille: She, presumably the mother, was asking he be removed from guardianship of Francois Ducharme because she had turned 21, and had fulfilled her obligation.

Note: The 2nd family in question is only mentioned so far only in Fr Chiniquy's ledger , St Anne's Catholic Church
Sept 10, 1854 baptism of Pulcherie Mullen born Sept 8,1854 to James Mullen and Rosalie Morissette
Oct 4, 1856 baptism of Jean Baptiste Thomas Mullin born Oct 3, 1856 to James Mullin and Rosalie Morissette
Chronology is close enough to first church records of Francois Family - the marriage of dau Marguerite and Antoine Cheffer in 1853, that Rosalie James could also have been a dau. and spouce of Francois Family from a union prior to migration.. or at least prior to connection to St. Anne's church, or perhaps an interfaith marriage.
Awaiting County Gen. Soc. Lookups help, but possibly need access to Canadian records.