It is very important to ensure that you define the appropriate Link Conditions.  In the example of 'Customers' and 'CustomerOrders' if you did not define any Link Conditions you would retrieve every Customer Order on your system every time you found a Customer.

Clicking on the 'Add' button will open up the Link Condition form where you can define your Link Conditions.  Alternatively click in the 'Allow manual editing' Check box to write your own conditions in the List View.

There is also an option to automatically create a Link condition by selecting the 'Suggest join based on indexing' button.

After they have been created, your Link Conditions are displayed in the List View, as shown below.

To Delete, Edit or change the order of a Link Condition, first select it by clicking on it in the List View.

To delete the selected Link Condition you then click on the 'Delete' Button.

To edit the selected Link Condition you would then click on the 'Edit' Button to open up the Link Condition form.

To change the order of the Link Condition click on the Up or Down arrow to move the selected condition up or down the list of conditions.

Once you have created all your conditions, either through manually editing, or by using the Link Condition form, you can then click on the 'Next >' button to move on to the last stage, the Link Wizard - Finished screen.