C# - Save Updated Object In Generic List?

I am trying hard to update a business object inside a List<>.

I am using a checkbox list

When a checkbox list item is clicked I check if it exists, if yes I mark it as Dirty (means the user unchecks an item)If not, I add a new item to the list (means the user clicks a new item)and store it in view state

How do I update the Generic List with the Dirty Object ?
On form update, do I foreach and make separate lists of dirty and new objects to send to DB layer or would you recommend any other way ?

Here is my code.

protected void cblExclusions_SelectedIndexChanged(object sender, EventArgs e)
{
if (cblExclusions.SelectedIndex != -1)
{
ftExclusions myExclusion=new ftExclusions(); // Business object

[Code]....