Can I create multiple new records through a portal

Hello,

I am completely new to FileMaker and I am trying to create a purchase order database. I need help with creation of multiple new records in a related table through a portal (or other way).

I have three tables: "orders", "suppliers" and "products". These are connected by the following relationships:

"orders:SupplierName = suppliers:SupplierName" and

"orders:productID = products:productID".

I would like to be able to create new records in the "suppliers" and "products" tables through filling up the purchase order layout. I created a portal for supplier displaying related fields (city, street etc). If I enter into the orders:supplierName field a new company and then address details into the portal, Filemaker correctly creates a record in the Suppliers table. This is working fine for suppliers (there is only one supplier per order). However I have a problem to create multiple new records for products in the products table. I have again an orders:productID field - repeating 20times. Next to it is a portal with also 20 lines. When I enter a new product ID and then related information (product name, price etc) into the portal, it creates the first and only first record correctly also in the products table. However, any further new productIDs entered create new records BUT with the same productID (as the first item). I cannot figure out how to do that. Ideally, user can enter multiple products on the order layout and all new products will be automatically entered in the products table. I am sure it is simple, can someone please help.

Thank you.

Martin