My great-grandmother was married to my great-grandfather's brother before she married my great-grandfather, and my great-grandfather married my great-grandmother's sister after he was married to my great-grandmother. Of course, in both cases they were a widow/widower.
I know marriage to a deceased husband's brother or marriage to a deceased wife's sister was common, but how common was a double whammy of remarriages among the same couples - wife married to husband and his brother, plus husband married to wife and her sister? All three marriages occurred in the same town in Sicily.
Also, is my great-grandfather's brother only a great-grand-uncle and my great-grandmother's sister only a great-grand-aunt, or are they more than that?
The marriage of the great-grandfather's brother with the great-grandmother had produced one child who died in infancy. What relationship is she?
