Families function in ways that are influenced by culture, environment, individual personalities, and the number of people sharing a home. It is becoming more rare, but many Japanese children still live in multigenerational homes with grandparents and sometimes still unmarried aunts and uncles.
When speaking about your own mother to someone else, you call her haha. When you speak to her directly, a variety of terms are possible. O-kaa-san and kaa-chan seem to be the most often used names for mothers. Some families use the term Mama, or sometimes Mama-chan, but that is a recent trend.
Solving disputes between siblings and classmates is easy in Japan. You have to play a game of janken (“rock, paper, scissors”). Janken is the accepted, ultimately fair arbiter of disputes. You will often see groups of students whipping out one of the three hand gestures: gu (“rock”), choki (“scissors”), or pa (“paper”) to settle any problem.
Other family members, as a sign of intimacy, are referred to with the suffix -chan instead of -san: too-chan (“father”), nee-chan (“big sister”), nii-chan (“big brother”). Sometimes kids attach these familial terms onto the sibling's name: Yumi-nee-chan. Using the terms baa-chan or baa-baa (“grandmother”) and jii-chan or jii-jii (“grandfather”) instead of o-baa-san and o-jii-san also reflects a familiar relationship.
Younger siblings may be addressed by name, but no suffix will follow. Often, a more casual version of “you,” like kimi or omae, is used in place of a little brother's or sister's name. You would never use either of these words when speaking to someone older than you or of a higher status than you.
Rarely will you see Japanese parents disciplining their children in public. Kids can sometimes be overheard describing their moms as demons, however, so you know that parents are disciplining their children at home. Mothers, too, describe getting angry as tsuno ga deru (“my horns come out”). If you need to discipline one of your guests, it is best to do it privately if at all possible. A public reprimanding will likely embarrass the child and make the rest of the trip rather miserable.