RJ, it was Anne Calvert-603, step mother of Katherine Marsham, born about 1644, who first married Baker Brooke, Sr, then married Henry Brent, and then married Richard Marsham. Anne would have been aged about 51 when she married Richard, who would have been about 57 at the time, so one would not expect to see any children of this marriage.
To my knowledge, Anne Calvert had children by her first husband Baker Brooke Sr, but not by her second Henry Brent or third husband Richard Marsham.
Katherine Marsham, Marsham--8, daughter of Richard Marsham and his first wife Katherine (probably nee Fisher) became the stepdaughter of Anne Calvert Brooke Brent Marsham, and married Baker Brooke, Jr, son of Anne Calvert's first marriage to Baker Brooke, Sr, and then after his death married Samuel Queen. Katherine Marsham-8, born in 1669, had children by both Brooke, Jr. and Queen.