The Swiss authorities online
The new legal provisions on names (since 2013) make it easier to change your name after a divorce.
Both people keep the name they took when they got married unless they wish to revert to their old name.
You can change back to the name you had before you got married at any time after the divorce. All you have to do is to make a declaration to the civil register office.
The divorce has no influence on a child's name. It can only be changed for important reasons with a name change application.