Unity (not Ursula) Croshaw was probably born in the 1640's. She was the daughter of Joseph Croshaw, not his wife. Her grandfather, Raleigh Croshaw was also married to a woman named Unity. They were married in England before they came to America. Raleigh arrived in the second supply in 1608, his wife arrived on the Bona Nova in 1620. This family had nothing to do with Powhatan and his family - Unity Croshaw was the first generation of the family born in America and she was born long after Powhatan was dead. Her birthdate is uncertain but she had married Col. John West by 1664. Unity and her husband ended up inheriting her father's lands when her brother died young. She was still alive in 1693 when she relinquished her dower rights to a property.
See Dorman's Adventurers of Purse and Person, Fourth Edition, Vol. 1 A-F pp. 769-773