Here is what I have about an Emma-Diana Ducharme (my # 10687): she was the daughter of Pierre Charron-Ducharme + Rose Robillard-Brault, born Feb 10, 1858, in Berthier, QC.
Pierre and Rose were married on August 30, 1858. They had 10 children between 1859 and 1876, but 7 died in infancy. The living ones were Emma, Henriette-Valérie, and Olivine Louise. That agrees whith your data about Emma having 2 sisters.
Pierre died quite young (Oct. 3, 1876). I dont have Rose death's date. Their 3 daughters disappear from Québec's registers, so likely they went to the USA. It's interesting to know that 3 brothers or sisters of Pierre went to Colchester and Winoski, VT.
So I believe that we can say that your Emma is the one described above.
Could you give more details about Emma? Dis she got married, and if so, when and where?