We have the following children showing up for those parents:
1-Marie Philomène Quimeneur dit Laflamme, b 26 Feb 1847 bapt 27th Ste-Marguerite-de-Jolliet (Dorchester); married Napoléon Audet dit Lapointe 20 Feb 1870 Ste-Hénédine (Dorchester)
2-Joseph Octave Laflamme, b 31 Mar 1849 bapt 1 Apr Ste-Marguerite; died 27 Jul 1849, buried 28th Ste-Marguerite @ 4 months
3-Joseph Octave Laflamme, b 5 Jun 1850 bapt 7 Ste-Claire (Dorchester); died 1 Aug 1850 buried 3 Aug Ste-Marguerite
4-Marie Césarie Laflamme, b 24 Oct 1851 bapt 25 Ste-Marguerite; married Maxime Lapierre 21 Nov 1876 Ste-Marguerite
5-Joseph Godfroy Laflamme, b 8 Mar 1854 bapt 9 Ste-Marguerite
6-David Laflamme, b & bapt 21 Aug 1857 Ste-Marguerite
7-Joseph Théophile Laflamme, b & bapt 8 Oct 1861 Armagh (origin stated as NOTRE-DAME AUXILIATRICE DE BUCKLAND); there is a duplicate record of this baptism in Buckland.
-Marie Cédulie Laflamme, of age when she marries Charles Laflamme 4 Mar 1878 Ste-Marguerite. Her birth and baptism are on 28 Nov 1855 in Ste-Hénédine (Dorchester), it reads Marie Ségulie (sic) Laflamme. https://www.genealogiequebec.com/Membership/LAFRANCE/acte/5591476
is the Drouin Institute link (paid site).
One reason you could not find her is that her mother's name gets written as all sorts of things which have really nothing to do with Nadeau. Obviously not present at baptisms.