Data List Insert new problem

[Ed Dror]

Hi there,

I'm using Wisual Studio 2005 Pro with SQL server 2005 Dev on XP SP2

I have two tables
Generic Item table (GN_ID) PK
Color Table (Color_ID) PK and GN_ID FK
very simple one to many relationship (one Generic Item can have many colors)

I created a Dropdown list that select items from Generic Item table
Then I created a Datalist control based on the GN_ID in the dropdown list
with Edit and new Button
Until here everything was very simple and work just fine

when I pick a Generic Item the data list show all color that belong to this
item.

Now when you click on new button the GN_ID field become empty and I want to
preserve that GN_ID
I don't want the user to enter the GN_ID every time they enter a new color
based on GN_ID from the Generic Table

Is there any way to read the GN_ID from cache?
Or create a trigger? if so how

Thanks,
Ed Dror