WWI Era Adult Fiction
Ever After, The Light Heart and Kissing Kin / Elswyth Thane (Are you familiar with Thane’s beloved Williamsburg novels? She is one of my all time favorite authors, and if you don’t mind starting mid-series, I will let you start with books 3, 4 and 5 above which involve the Day (from Virginia) and Campion families in England prior to and during WWI. As Thane was American, you won’t need to worry about the unflattering depiction of Americans often encountered).
Sabrina / Polland (Set in Ireland before WWI, this is the story of an aristocratic family not unlike the Crawleys. I wish someone would make a miniseries of this book!)