Since my earlier post, I have found Catherine's father, William Brenton, born abt. 1595 at Hammersmith, Middlesex. This William also died at Hammersmith, though I don't have a date of death for him. However, I think there is a possibility that the William you've described as being Catherine's brother is this same William, whom I have found listed as her father (www.familysearch.org, I think). If the date of death for Catherine's father was 1673, he'd have been 78 at death, which fits well. On the other hand, if you've found a will in which he names Katherine Cooke as his sister, this would have to be my Catherine after she married Walter Cooke, as her maiden name was Brenton, of course. This makes sense. Her birthdate of 1628, however, makes a 33-year difference between she and William that is rather unlikley if they were siblings. Therefore, I'm inlcined to believe the William I have is, in fact, Catherine's father, as noted, rather than her brother.