You need a join table in between when you have many to many relationships. I don't really think your example has much in the way of many-to-many relationships.
In fact, in the example above you need 4 tables really.
One customer can have many invoices and each invoice can have many items ordered. Products is a reference table where the price of the items is looked up when entered in the OrderItem record. An Invoice is a 'holder' of multiple items.
At no point would an invoice have many customers or an orderitem relate to many orders.
Which tables will be linked to the 2 portals? I want my data entry to be in the portal itself both for the parent and the child based on my example. Thanks
Well... that all depends on the perspectives you want to take.
You may want to be able to enter invoices & invoice-items from the customer record
from the invoice enter lineitems and the customer all in the same layout....
..... many ways to do the same thing.
Relationships are never single one-size-fits-all scenarios. You may end up with relationships like:
• Customer-Invoices, Customer_Invoices_Overdue, Customer_Invoices_Paid
• Product-Invoice-Items might show data about purchase of a product found on many Invoices.
I suggest you look closely at the Invoices template files from your starter documents (New From Starter Solution).- Lyndsay