Thanks Frances. When one puts the 3 wills together, ie, Thomas Looney 1691 ( mentions bro in law Rbt Cannon, and later mentions Ann Cannon and dau Margt), plus Robert Cannon's 1699 (mentions 4 daughters including Margt, and unnamed wife but no sons mentioned), plus Ann Cannon als Looney a few yrs later (I forget the year, but recall it mentions 3 sons, two of which abroad, but no daughters mentioned, plus a Looney cousin), there might be some useful clues. Thomas Looney has a father alive ( I think Robt d 1699), brother William and probably sister Ann married to Robert Cannon.
The exec of Ann was her son Philip Cannon, and there's a burial and will for a Philip Cannon, Maughold, very soon after. I'm writing this from memory, as my database isn't available to me right now.