San Francisco-based CP National said it increased its investment in Luz International of Los Angeles to about 11% from 6%. CP National also has an option to acquire up to a 20% interest in Luz during the next two years . . . Dragonair, the Hong Kong-based airline, has signed a purchase agreement for two McDonnell Douglas MD-11 wide-cabin transports and an option for one more . . . British Petroleum extended by 20 hours a tender offer for all the shares of Standard Oil that it doesn't already own.