Yes you can. You do not have to be a family member to benefit from someone else's frequent flier miles.
American Airways offers a frequent flyer program that can be used on any of their flights, including international.
Thai's program is called Royal Orchid Plus. In addition, Thai Airways is a member of Star Alliance. Members of any other Star Alliance frequent flyer program can earn miles for their flights on Thai Airways, can redeem miles for award flights on Thai Airways, and can benefit from elite status when flying with Thai Airways for things such as early boarding and lounge access.
Singapore is a member of Star Alliance. Its U.S. members include United Airlines and U.S. Airways. U.S. Airways may not remain a member, since it is merging with American Airlines, but United will. Members of any Star Alliance frequent flyer program can earn miles for flights on any member's flights and can redeem miles/points for flights with any member.
British Airways air miles are available for members of the airline's frequent flier program. To sign up, a flier simply needs to visit their website and then book a flight to start earning points.
The frequent flier program at British Airways, the Executive Club, can be joined directly from the British Airways website. You only need to provide basic identity information before you are on your way to earning Avios that you can spend on flights, hotels, and car rentals.
Having an account at SkyMiles allows someone the ability to collect points that can be used to book free flights aboard Delta airways. Skymiles is Delta airways customer loyalty program designed to improve customer satisfaction and reward frequent flyers.
All major airlines have frequent flyer programs. They track the flights that program members take. After a certain number of flights, members are eligible for awards such as free flights or upgrades.Because many people have the same name, and addresses change, airlines assign each member of their program a number. (It may contain letters, but it's commonly called a "number" anyhow.) This is the person's frequent flyer number or flyer number. If a person is a member of more than one program (you might as well be if you travel a lot, it costs nothing to join them) the numbers will be different for each airline.
Emirate Airlines hosts a frequent flyer program that offers free flights and upgrades on flights, special offers, priority check-ins, and bonuses of 150% extra miles.
the frequent flier customer loyalty program used by Delta Airlines--allows members to accrue miles through travel with the airline or its partners. Members can later redeem the miles for free flights, travel upgrades and even shopping opportunities, once they reach a specific membership category.
The Lufthansa "Miles and More" program offers the chance to earn frequent flyer miles on their services. These miles can then be redeemed for flights and upgrades.
American Airlines Advantage, Delta Sky Miles, and US Airways Dividend Miles are rated as very good programs by Business Travellogue. The tell you what the rewards are and how to get them at http://www.businesstravellogue.com/best-frequent-flyer-programs.
Basically no frequent flyer program offer their frequent flyers upgrades on international flights - never mind liberal upgrades. On international flights the Business and First cabins are premium and they do not want the product diluted. However, during heavy travel periods, airlines will upgrade frequent flyers if they oversell the economy cabin. These upgrades are called OpUps - Operational Upgrades. They are done for operational reasons and not to reward a frequent flier. The best chance for one of these is to fly on routes that are heavy on economy and low on business travellers and that use a plane such as the Boeing 757 rather than a Boeing 767/777/747 or Airbus A-330/340. An example of the is JFK-Dublin on Delta airlines.