Relationship behavior on entities

Greetings,

Here is the situation: I have three entities: Accounts, Orders and Orders Items. Accounts submit orders and the from the order items we add the order items.

I would like to have order items related to orders and the orders related to the account in a way that you would also relate the order item to the parent account.

What is the way to go to that?

I changed the N-1 Relationship of the lookup field between the Order and Account and the N-1 Relationship between the Order Item and the Order, both of them are setup as parental, but it does not seem to work because I see the records on the sub-grids I have created on the forms and I have set them up to show only related records.

Am I doing something wrong?

Any help is welcome.