Family Reunions always have seldom seen cousins/relatives.
Line everyone up single file starting with the youngest to the oldest. The first in line turns around to face the line of relatives and announces: I Am (name). The second person turns around and announces: I Am (name) and You are (name the person behind you). The third person has to give his name and the names of the two people behind him and so on until the last person has to name everyone in the line. If you miss a name, you have to go to the end of the line where you will have to say everyone's name!
What's really amazing is that often the most elderly grandparents can easily get all the names correct.