To create new types of relationships between customers, we will go to System -> Additionals -> Relationship Types

We will see the following screen, with the list of all the types of relationships that we have already. To add new types click on New    , to edit an existing one press , and to remove them press

As in this tutorial we want to create a new one we will click on the "New" button, then we'll see the next screen

In this window we will write the type of relationship and its inverse relationship. For example in the relationship "Son", the inverse will be "Father / Mother"