Before using this procedure, make sure you've set up your table relationships correctly.
You can use this procedure to create a form and two levels of subforms that have a one-to-many relationship. The main form has a one-to-many relationship with the first subform, and the first subform has a one-to-many relationship with the second subform.
How?
Note Make sure to select the Tabular (the equivalent of Form view) option when the wizard asks what layout you want for the subform. If you select the Datasheet option, you won't be able to insert a subform inside the subform.
How?
Microsoft Access creates another subform inside the first subform and creates a form for the subform.
Notes