Hi Amar,
I am afraid you do have to mention them...even if they're not your fault. If you don't your insurance could be invalidated.
Annoyingly, i also had someone go into the back of my old rover 600 about 5 years ago.
Even though they admitted liability and their insurance paid out £1.4k for the Rover, it still affected my premiums...people often don't think it will but it does.
Without wishing to sound condescending but how old are you again? I remember you were the youngest 8 driver i knew when you first joined (i believe 18) but this given that you've got 2 claims and you're driving the S/A8, it may be worth staying on as a named driver but getting yourself on as a primary driver on a small hatch if you've got another vehicle in the family?!
...hate to ask what they'll quote you for your premium
Oli