There may not have been any children. In 1881, in Lot 24, Queens Co., PEI, Sophie Aucoin (33) is a widow and lived with a Gallant family which included Sophie Gallant (75) also a widow. There was also an 'Apoline' Gallant (5), so if Sophie, Jr. had a sister, Appoline b. ca. 1831 then this would appear to have been the Sophie Aucoin you seek and no children seem to be listed with her.
The head of the family is Onesime Gallant (39) with a wife, Philomene (40). From baptismal records Philomene is also a Gallant. Also Onesime was b. 16JUN1842 the s/o 'Grancois' and Sophie (Pitre) Gallant. Again, it seems that the widow, Sophie Aucoin, was the one you seek and she appears to have no surviving children. Appoline Gallant b. 2SEP1833 was the d/o François and Sophie (Pitre) Gallant.