Set Default Value for relationship names:
Select Settings | Default Values... or open the Properties dialog of particular object (e.g. Relationship Properties form) | right-click the form and select Default Values for Class.
In the Default Values window, select the catagory you want to set default values for. For example to set default relationship name, go to "Relationships" on the left. The right will display the options to set for relationships, one is noted as name.
For more details, please refer to Toad Data Modeler open the help file. Go to the Contents tab of the help window. Drill down to Projects and Models | Options and Configuration | Default Values.
There is also a list of variables to use for default values. In help, go into Projects and Models | Features | Application Variables.