Dear Sir,
I hope my letter finds you in good health. I am very pleased to receive an invite for attending Chris’s birthday party as well as disappointed that I would not be there to join the jollification.
In my humble opinion, it is an awesome idea to astound him and I think he is going to love it. Primarily, he loves surprises and he will be overwhelmed by seeing everyone. Moreover, he likes to have grand celebration on his special day. He will be captivated by seeing that you have planned it considering his taste.
I am working in a multinational company and I am going to USA for one month in June for some project. Owing to my work commitments, I would not be able to manage to come on that day. I am honoured to receive the invitation and already know that I am going to miss a great occasion.
However, I will be back by 8th July and we can have a small get together on that weekend at my place. I would highly appreciate if both of you along with Chris can stay with me on that weekend. We can arrange to go for safari or spend time on beach for a day.
I will wait for your yes and look forward to meeting you in July.
Yours lovingly,
[YOUR-NAME]