I do have some personal notes. Maybe they will help. Note the Mixon is referring to Megginson.
Entailed Lands Released 1718. Hening.Vol. 4 p75April 1718."An act to enable Michael Megginson of the County of King and Queen,to sell certain Lands in the County of Gloucester, entailed on him,and the heirs of his body, upon his settling other Lands of a greater value to the same uses".
In LAWS OF VIRGINIA,APRIL 23 TO JULY 10, 1718:Whereas Michael Meggison ( note the different spelling)Alledged that John Meggison His father willed him 130 acres in the Parish of Abingdon in the County of Glochester, and that he would like to swape this land for 500 acres in the Parish of Saint John in the County of King William.The court gave to the said Michael Meggison, otherwise called Michael Mixen, 250 acres on Boot Swamp, a part of the 500 acres requested.
A Pattent dated Aug 16, 1715 was given.( Land Patent Books, Land Office at Richmond)To Michael Mixen, 50 shillings, 500 acres lying on south side of Boot Swamp, adjoining Col. Jennings...St.Johns Parish..King William County,bounded by Major Bartelott.. (Just a few years later this part of KW was cut off into Caroline County).
Diaries of George Washington, vol. III, p.87 April 1,1787 "At home all day (Mount Veron). Mr. Hunter, Mr Runey, Mr Porter, Dr Craik, and a Capt Mixon dined here. All except Mr. Hunter went away after it."