This may not be relevant after all this time but I have a copy of some research that indicates an Alexander John CHAMBERS married Fernanda Margaret DE MAMIEL in 1860 (I think in either Ireland or North America), his brother Coote Mulloy CHAMBERS married her sister Cesarine Sophia Jane DE MAMIEL about 1866, I believe either in Vancouver or on Vancouver Island.
I understand Cesarine Sophia Jane died in childbirth in 1867. I do not know if the child survived.
HellyMelly