MB3 194b Caring for Children - part 2 (343:1); How to Observe Shabbos When One Loses Track of the Days (344:1)

A father's obligation to stop his child from chilul Shabbos, other transgressions. If a child does a melacha on Shabbos on his/her does everyone have to protest or only the parent?

Compensating for damage caused by one's child.

On what day should someone keep shabbos if he/she loses track of what day of the week it is? When can or can't they do melacha?