Limit the Promotion for Selected Order Line Item Only

Hi,
   We have promotion definition as follows

Promotion Name : Infiniti Connection US - 1 Year Promotion
     Under Pricing Tab
         Product Name = Infiniti Connection  Price Override = 169 USD

We have Order as follows

Order Line Item Status:  Product                          : Promotion
Existing                       : Infiniti Connection

New                              : Infiniti Connection

Here When we Select promotion for second line item the promotion getting autamatically applied for All the Line Items with the Product Name : Infiniti Connection.
But our requirement is to apply promotion only for Second Line item with Status New .
Please advise how to aviod the promotion getting applied all the items.

Please advise what is happening behind when we select the Promotion ?