Play has long been touted as a form of therapy for children with social issues. In particular, it can help develop kids' attention spans and social skills. Board games are a particularly great resource for large family gatherings because they foster development while engaging the whole family in a productive, fun activity.
Although many kids' games these days are elaborate, less is more. The Learning Disabilities Association of America notes that fostering empowerment is an important parental strategy when raising a social issues child, but complicated games can be hyper stimulating, as well as frustrating, to kids who are failing to grasp the basic concepts. Consider straightforward games such as Clue, Chinese checkers, and The Memory Game to develop both cognitive and social skills. 
Chinese Checkers (6 and up)
Chinese Checkers is a wonderful example of a simple game that has endless benefits for children with social issues. First and foremost, it teaches kids to develop a strategy to get across the board, an ostensibly basic principle that can have profound effects. Chinese checkers also encourages kids to anticipate consequences.
Clue (8 and up)
The classic whodunit game is a master class in problem solving. By providing a safe outlet in which to see the consequences of impulsive decisions, kids will learn to be more objective, rather than making emotional decisions. They'll also develop skills like organizing and prioritizing information.
The Memory Game (2 and up)
The Memory Game is a good way to develop children's focus. Parents can manipulate the game, setting up the matching cards closer together so it's easier for younger or less focused children to find a match. Then, you can increase the challenge by spreading the matching cards farther afield. 
Board games help children (and adults too) learn to manage failure. Recovering from disappointments and adjusting your tactic the next time around is an invaluable life skill for everyone. Give it a shot at your next family gathering!