CHESAPEAKE, Va. — Dollar Tree Inc. last month announced two new executive hires as the company continues to overhaul its leadership team. Michael Creedon Jr. joins Dollar Tree as its chief operating officer, and Pedro Voyer assumes the role of chief development officer. Creedon comes to the discount retailer from Advance Auto Parts Inc., which he joined nearly nine years ago and since last year has held the title of executive vice president for U.S. stores. Creedon replaces Thomas O'Boyle, who left Dollar Tree this summer along with four other executives following a board shakeup instigated by activist investor Mantle Ridge LP, one of the discount retailer's largest shareholders.