Abigail Knyvett, also spelt Knyvet, was born about 1540, and married Martin in 1560 at Morley Saint Botolph, Norfolk. She died December 15, 1623.

A Monumental Brass in Wacton Church recorded the death on December 15, 1623, of Abigail Sedley, daughter of John Knyvett of Ashwellthorpe, and late wife of Martin Sedley.

National Archives (UK)
Reference: KNY 455 371 x 9
Settlement prior to marriage between Martin Sedley gent. and Abigail sister of Thomas Knyvett Esq. re manors called Some Halle (in Barford) and Barford Halle alias Flynte Halle, (1557).

Reference: KNY 654, 655 372 x 5
Martin Sedley, Morley. Financial negotiations for Sir Thomas Knyvett and building barn and reed thatching Sedley's house, (1583, 1599).

Reference: MC 44/17, 500 x 1
Letter from Robert Martin to his father-in-law Martin Seadly, Morley Hall, re gift of bucks by Thomas Knyvett, (1594).