If I choose, I will eat dinner with their families, because it may be the last day that got together happily, or may be eaten with some people in my family for the last time.
If I choose not to eat dinner with my family because it may be the last day to be together happily or may not eat with someone in the family for the last time.
If I had a choice, I had dinner with the family, because that day may be the last day live with happily or may have to eat with someone in the family for the last time.