I don't see any way that Avis Partin could be a wife of William Carter. William's first wife may not have been the Avis that he claimed as a headright, but whoever she was it wasn't the Avis Partin in the muster. William was married to Alice, his third wife by 1637. CORRECTION: Avis Turtley is listed by name in William's 1636 land grant, original and image at the Library of Virginia.
The originals of the muster roll are in England. The roll of 1624/5 as transcribed by Dorman lists the Partin family as:
Robert Partin aged 36 yeares in the Blessinge in June 1609, Margaret his wife aged 36 in the George 1617,Robert, Avis, Rebecca theire children aged 4 Months, aged 5 yeares, aged 2 yeares
Avis Partin was born in 1619or 20 since she was 5 in 1625, the year of the muster. There is no question that William Carter was married by 1629, quite possibly by 1626. Avis, her sister, and two other little girls were raped by a servant when she was seven years old. Avis, her mother, and her sister were all sentenced to be whipped, the mother for failing to promptly report the crime and the children just in case it was their fault. The rapist, Thomas Hayle, was executed. Minutes of the Council and General Court, pp 149-150. https://archive.org/details/minutesofcouncil00virg/page/148/mode/2up?q=Hayle