Meanings
in the pluralpeople who marry siblings, relative to each other: women whose husbands are brothers, etc.
in the pluralpeople whose siblings are married to each other, relative to one another: women whose brother and sister are married, etc.
in the pluralpeople who marry siblings, relative to each other: women whose husbands are brothers, etc.
in the pluralpeople whose siblings are married to each other, relative to one another: women whose brother and sister are married, etc.