The Vale noblewoman who joins the Lords Declarant in the novels is Anya Waynwood.
Anya is Lady of Ironoaks and the head of House Waynwood, one of the Vale of Arryn’s powerful vassal houses. After Lysa Arryn’s death, Petyr Baelish becomes Lord Protector of the Vale and guardian of the young Lord Robert Arryn. Several Vale nobles distrust Baelish’s rule and form the Lords Declarant to challenge his authority and protect Robert.
The group includes Yohn Royce, Gilwood Hunter, Horton Redfort, Benedar Belmore, Symond Templeton, and Anya Waynwood. Their confrontation with Baelish takes place during the events of A Feast for Crows. Although they arrive in opposition, Baelish exploits divisions among them and persuades the lords to give him time to prove his fitness as Robert’s guardian.
Anya is also important through her ward, Harrold Hardyng, a potential heir to the Vale. A common mix-up is Myranda Royce, who is Anya’s fellow Vale character but not one of the Lords Declarant’s signatories.