Well, you have gotten into some tricky families with your recent questions. Fortunately, Isle Madame is where my grandparents were born, and I have reconstructed just about all of the Acadian families from there. As you know, the parish records there have many gaps, so there are quite a few things that we will never know, but the connections can be worked out, provided one is prepared to dig deeply enough. I have in my notes some information about your correspondent's ancestor Anne or Annie Girroir. (That's the way the name is normally spelled locally, following Father Hubert Girroir's lead.) I do not have Anne's exact birthdate, but we can estimate it from her age at the time of the 1871 census. On Jan. 3, 1875, at Cambridge, Mass., she married Alfred Grenier, son of Isidore Grenier and Louise (Heins) Hains.
As you say, Anne Girroir's parents were Gaétan Girroir and Anne Petitpas. Gaétan and Anne were married at Arichat, Jan. 9, 1837. The church record of their marriage was lost when the Arichat glebe burned down in Nov. 1838, but the date of their wedding has been preserved in a listing of marriages at Arichat that was published in the Novascotian newspaper in Feb. 1837.
Incidentally, Gaétan Girroir died aboard ship in 1881 in circumstances that were thought sufficiently remarkable so as to deserve notice in the Moniteur acadien of Dec. 8th. Here is an English translation of the announcement: "G. Girouard of D'Escousse, C.B., died recently while on his knees saying his prayers on a schooner from Prince Edward Island. It is supposed that apoplexy was the cause of his death. He was well known by all of Isle Madame. He was about sixty years old, married, and a pilot by profession."
Gaétan Girroir had a first cousin once removed named Bernard Pâté who became very much interested in genealogy during the 1890's. One result of Pâté's interest was his compilation of a listing of the descendants of his own maternal great-grandparents, Prospère Boudrot and Esther LeBlanc. Prospère and Esther were also Gaétan Girroir's maternal grandparents, and Pâté's compilation shows that Gaétan's parents were Michel Girroir and Marie Boudrot.
Michel and Marie were married at Arichat about 1814 or so. Pâté tells us who her parents were. As for Michel, a series of land transfers gives the clue to who his were. Through this series Michel and his siblings received parcels of land from their father, Jean-Baptiste Girroir. The deeds show that Jean-Baptiste was married to a woman named Gertrude. This lady's burial record still exists in the Arichat parish register, and it shows that she was a Landry. Her age in this indicates that she was the same Gertrude Landry whom Father Bailly baptized at around the age of twelve in 1771. She was a daughter of Jean-Baptiste Landry and Marie-Josèphe LeBlanc. Dispensations prove that Gertrude was indeed Michel Girroir's mother. Her husband, meanwhile, was a son of Pierre Girouard and Cécile Detcheverry, who appear in La Roque's census of 1752.
Placide Gaudet thought that Cécile Detcheverry's husband was a son of Pierre Girouard and Marie Doiron, but I think it is much more likely that he was a son of that Pierre's son Claude (DGFA, p. 724). Claude and his wife Madeleine Vincent fled to Île Royale just a little before the time when Pierre Girouard married Cécile. It would have been the most normal thing for Pierre to have accompanied them, as their son, rather than as Claude's half-brother. And once Pierre married, his fortunes were tied up with those of his wife's relations, which explains why he did not move on to Québec with his own mother and father.
The Petitpas lineage can be reconstructed, but I cannot give you a marriage record for Régis Petitpas and Marguerite Landry. They were most likely married at Arichat around 1804, and all the records there prior to 1839 were lost in a fire, as I mentioned in an earlier message. Notwithstanding that, I can identify Régis Petitpas's parents, but not those of Marguerite Landry. Régis was a son of Pierre-Paul Petitpas and Gertrude Poirier. This relationship is shown by a will drawn up Mar. 31, 1836, by Régis's step-father, Janvier Josse. The will specifically describes both Régis and his brother Pierre as Janvier's step-sons. None of the marriage records of any of Gertrude Poirier's children exists, but her burial record in the register of D'Escousse indicates that she was Janvier Josse's wife. She died Sept. 7, 1832, and was buried the next day, at seventy years of age. Her widower's will does not mention her by name, but it nonetheless proves that she was the same Gertrude Poirier who had married Pierre-Paul Petitpas. The given name of her first husband is meanwhile provided by the only surviving baptismal record for one of her children, which is in the register of Carleton, Québec. This record is dated Apr. 25, 1785. Unfortunately, it omits the child's given name, but I believe it is her son Pierre's baptism, because the militia census of 1813 shows that he was born around then. Her son Régis Petitpas was a couple of years older in the militia census, so he was born about 1783. He died in 1837, and was buried at D'Escousse on Mar. 22nd of that year.
Gertrude Poirier's age at death suggests that she was born in 1761 or 1762, and among the children baptized by Father Charles-François Bailly at Arichat in 1771 there was a Gertrude Poirier who had been born Sept. 17, 1761, and we can be confident that this was the same person. She was a daughter of Michel Poirier and Judith Richard. Incidentally, one of her sons by her second marriage was named Michel, obviously after her father, particularly when one considers that I have found no boy named Michel among the Josses prior to the birth of Gertrude's son.
The evidence concerning the parentage of Pierre-Paul Petitpas is less clear. The godmother of Pierre-Paul's child in 1785 was Marie-Hélène Petitpas. Father Bailly baptized this person, too, although not at Arichat, but at Chezzetcook. Marie-Hélène was a daughter of Louis Petitpas and his second wife, Marie-Josèphe Dugas. I presume that she was asked to be Pierre-Paul's son's godmother because she was the child's aunt. I think Pierre-Paul was probably a few years older than his wife Gertrude Poirier, and that he thus must have been a son of Louis Petitpas's first marriage, to Madeleine Pouget.
You can pick up the continuation of the Petitpas line on page 1298 of the DGFA.
On the Landry side, I can tell you that a few of Marguerite Landry's children and grandchildren married Landrys or Landry descendants from River Bourgeois, so it would appear that she did not herself descend from that branch of the family. The rest of the Landrys in Richmond County descend from the three brothers Jean-Baptiste, Joseph, and Alexis Landry from family No. 17 in the DGFA (page 944), and so it is likely that Marguerite descended from one of them, but I have been unable to make the exact connection. The trouble here is that there are a number of unknowns. For example, in the family of the eldest of these three brothers, Jean-Baptiste, there were two sons, Joseph and Dominique, who are not known to have married, but they might have, and either could have become the father of this Marguerite. It is also likely that Jean-Baptiste's eldest son, also called Jean-Baptiste, remarried after the death of his wife Marie Dugas at Miquelon in 1777. Jean-Baptiste fils was only thirty-eight when he became a widower, and I have land records that show that he was still living at least twenty-seven years later, in 1804. Normally, a relatively young man at that time would have found himself another wife, so he too might have been Marguerite's father. If any of these speculations could be proved, we would then find that Gaétan Girroir and his wife Anne Petitpas were second cousins. Now, if only we had a couple of more years of the records at Arichat, we might have the marriage record of that couple from 1837, and the dispensation they received might well shed a lot of light on this problem. In the absence of that, however, we will just have to look elsewhere for clues regarding who Marguerite Landry was.