Need Suggestion

Hi,

I'm creating a birthday invitation card for my eldest uncle's 100th birthday dinner. I would like to have a reply card attached on it. But im not sure how to write the topic to make it sound more polite and respectful when asking people whether or not they are attending the birthday dinner.

I have some suggestions here:

1. The favor of your reply is requested. Please kindly reply on or before 31 June 2006.

2.The courtesy of a reply is requested by 31 June 2006

3.Please kindly response before 31 June 2006.

Can anyone help make up my mind? I would like to hear your opinions too on this.

Thanks