Unexpected changes in relationships can put stresses on all of them. Characters must be examined from each facet of the unique family dynamic to see how they’re put together.
Deaths, births, marriages and divorces are all stressful events that change a character’s family. They’re not to be used lightly, and they show a character to his limits. Home and family are always things that define a person.
Add in a holiday or two, and things might be comedic, strained, or just plain ordinary. All angles can be shown to put the characters to light.