Twins. The Dragon's Dove Chronicles

From the award-winning, critically acclaimed pen of Kim Iverson Headlee comes the fall of Camelot as you have never seen it before. The death of their mother knells the death of any hope for a joyful future for Gyan's identical twin daughters, Gwenhwyfar ("Yfarryn") and Gwenhwyfach. Their father, Arthur the High King, wastes no time in announcing firstborn Yfarryn's betrothal to Medraut-the man whom Gwenhwyfach secretly loves.
And Yfarryn is in love with Angusel's son Lannchu. The twins conspire to defy Fate and trade places. They know how ambitious is their scheme, for Yfarryn is trained in the domestic arts and Gwenhwyfach has chosen the warrior's path, yet the sisters are confident of success. Fate, however, shall not be defied. Incorporating ancient Welsh legends of the "False Guinevere" and "Feasting the Hungry Man, " and featuring many characters introduced in Dawnflight, Morning's Journey, and Raging Sea, this glimpse into their destiny, thirty years after the setting of those novels, reveals the destruction of Arthur's realm that's unique in all of Arthurian literature.
Praise for other Arthurian works by Kim Iverson Headlee:"Intense." USA Today (Dawnflight)"Entertaining." Publishers Weekly (King Arthur's Sister in Washington's Court)