There are no family documents in existence that I am aware of. Back in the 1700’s everyone relied on parish registers. That is why it took me 17 years to get to this point and it can only be proven by DNA.
Through Ancestry DNA I have specific matches to my 4GGM Genevieve Tardif the mother of Andre Ouellet who married Marguerite Cormier. I also have several matches to her mother my 5GGM Genevieve Roy and to her mother my 6GGM Marie Martin.
Prior to getting my DNA tested I did a process of elimination to all the Andre Ouellet born between 1740 to 1780 extracted from database from Quebec PDHR. Only a possibility of 2 Andre’s born in Quebec and did not die there no records of their death existed in Quebec. My ancestor Andre Ouellet born in Quebec and died in Memramcook New Brunswick Canada.
DNA matches lead me to only one of the Andre’s by searching for matches relevant to their spouses. My matches to descendants of Genevieve Tardif the wife of Jean Baptiste Ouellet were plenty and that could only be explained by Andre Ouellet their son being my 3GGF and he left Quebec met Marguerite Cormier in Fort Ste Anne present day Fredericton and came to Memramcook New Brunswick with her family that had to leave that area because they lost their land along the Saint John river . If you follow the timeline of Anastasie Melanson which is the wife of Francois Cormier and Marguerite Cormier’s parents you can track Andre & Marguerite’s journey.....
Biography and Timeline
Anastasie Melanson was born Aug 22, 1739 in Grand Pre to parents Paul Melanson and Marie Theriault.
When Anastasie Melanson marries Francois Cormier, the locations of her marriage and her chidlren's baptisms reveal the constant movement of her young family, which starts in Quebec, but continues in St Anne (Fredericton NB): 
1761 Aug 3 in St Pierre du Sud, Montmagny, Quebec: Twenty two yearo old Anastasie Melanson, daughter of Paul Melanson and Marie Theriault marries Francois Cormier. Anastasie is a widow of Claude Brun.
1763 24 Jan in St-Thomas de Montmagny, Quebec: The couple’s first child is baptized, a daughter Marie Cecile.
1765 24 May in St Anne de la Pocatiere, Kamouraska, Quebec: The couple’s second child, Marguerite, is baptized.
1765 St Anne (Fredericton NB): The families of her husband Francois and his brothers, including their mother Cecile Thibodeau, return to St Anne (Parish of Rivière St Jean, now Fredericton). Four more of Francois' and Anastasie’s children are born there:  Marie Joseph (1767); Francois (1772); Germain (1782); and Sylvain (1784). Anastasie is 45 years old when she gives birth to Sylvain.
By July 1783, the Cormier brothers have cleared 20 acres, which they occupy for 13 years. However, the Acadians of Sainte-Anne have not secured title to their farms. Grants to disbanded soldiers and loyalists are soon encroaching on what the Acadians consider to be their land. The property rights issue is described by the University of Moncton  :
• “Acadians living in Acadie after the Deportation did not have a quiet life. When they arrived in what is today's Maritimes, Acadians had no property rights, a part from a few exceptions. Many occupied lands to which the colonial administration considered they had no rights and were driven off when these lands were purchased. The War of American Independence, which brought a massive arrival of Loyalists in the Maritimes, also forced many Acadians to move away. This was the case with those from the region formerly known as Saint-Anne-des-Pays-Bas (today's Fredericton)”
1786-87. Learning of vacant land on the west side of the Memramcook River (known as La Pointe), about 20 families move, including the Cormier brothers and some of their married children . Their aged mother Cecile Thibodeau dies during the trip.
1788: Abbé Thomas Francois LeRoux of Memramcook describes these 20 families: "The 20 families from the St John River are very poor (which I want to correct). I have succeeded with some but others remain rebels. This is now my disgrace. I have supported almost all of them as much as I can, but I am obliged to buy grain for myself in order to live. If it were not for the glorious people of the St-John River, my flock would be wise and calm. I do not know which of these household heads are rebellious and arrogant. These families have not had spiritual support for 20 years with the exception of priests’ visits in 1768 and 1774."
1792: The so-called “vacant” land where the Cormiers settled had already been granted to Joseph Goreham and then sold to Joseph Frederick Wallet DesBarres in 1775 . On 5 June 1792 the Cormiers and others present a petition to the New Brunswick government complaining of the "extravagant" demands of DesBarres's agent, Mary Cannon, and arguing that his land should be granted to them in consideration of the substantial improvements made during their occupation. Their efforts are thwarted by DesBarres and his agents. The dispute will drag on among the descendants for 50 years.
The Cormiers’ farm is at L’Anse des Cormiers (Cormier Cove, New Brunswick, Canada).
1816 Nov 22 in Memramcook: Anastasie dies at the age of 77.