Research Notes:
The visitation of Gloucestershire states that "John Kemys of Siston com. Gloster" married "Margarett fil. et coh. Mauritii Russell mil. et Isabella uxoris." [1]
[1] John Maclean and William Crawshay Heane, eds., The Visitation of the County of Gloucester: Taken in the Year 1623, by Henry Chitty and John Phillipot (London: Publications of the Harleian Society, Vol. 21, 1885), 98, [GoogleBooks].