How can get a custom deal product using API?



I try to get a list of products related to a deal using the API.
When I add a product from the products list and use line items and associations, it works fine.

When I edit the product from inside the deal, the source product doesn't change.
How can I get the updated product for the deal?

Use case:
Create product P1/100$
Add it to a deal.
From the deal details, change the product name to P2 and the amount to 200$.
The original product in the products library is still P1/100$ (which is fine) but P2 is not in the list.
What API should I use to get P2 with the 200$ amount?


The data can be found in the Line_Item