Not show Child tables on the main screen

I have three tables in a One to Many, One to Many relationship. Lets call them Grandparent, Parent and Child. I only want the Main one (GrandParent) to show up on the screen when the user logs in. Then when the user chooses a record from GrandParent it will open all the Parent Records associated. Then the user can choose a record from Parent and all Child records associated with it will open.

I linked them one to many already, but on the main screen, when a user logs in, they see all three tables and can access them. I want the Parent and Child hidden from view and their data can only be gotten to if the user chooses the Grandparent record.

I hope this makes sense.

Thanks