Question about Dynamically added custom controls

1. This is the first page, where "sales project and contact Customer 1" is added manually. If you click "add next sales project and customer", the second image will appear.

Add a user control 2 dynamically. If you add another control, click the button. When I add it to 4, I delete the 3rd control items and the following page appears.

I have done all these added things, but when I write a modification page, I encountered a problem. Please refer

The primary key in my database is date, name, sales item, contact Customer:

My problem is:

As an example, the user submitted three "sales items and contact customers". After the query, the user may perform the following operations: add several user controls; delete one of the three user controls, delete and add them, or modify them on the original three. When I operate the database, insert or update may be used. During update, the original primary key has been selectchanged. How can I update it? It seems troublesome to control the User Control ID. In short, you may feel confused.