Setting: 17th century Scotland
Research Conducted: Google searches for "familiarity between family members 17th century scotland" "familial forms of address 17th century scotland"
My protagonist is the only daughter of Alexander Fraser, the second surviving son of the 7th Lord Lovat and 15th Chief of Clan Fraser (of Lovat). Her mother, Sybilla, is the widow of Ian MacLeod, 16th Chief of Clan MacLeod with whom she had seven children. One of these children, Sybilla, married Alexander's younger brother, Thomas, thus my protagonist's half-sister would have married her paternal uncle. My question, then, is how would she address these family members? Because of the marriage, her sister would have become her aunt and the couple's children would have been her cousins as well as her nieces and nephews. Would it be more likely that the marriage would have created a barrier of sorts between them so that she would have to address Sybilla as "Mistress Fraser" and eventually "Lady Lovat" when Thomas inherits the title due to an extinction in the senior male line? Or, would they maintain a more familiar address with one another as appropriate for siblings? What about the children? Would they refer to her as "Aunt"?
Truth is definitely stranger than fiction and I have no idea how to even go about researching this given that such matters of custom tended to have been inherently known and too commonplace to record and my searches so far have been useless. Any and all help you might provide will be greatly appreciated! Thanks in advance!