Dear Ms. Indu

I have filed I-485 and I-765 for myself and my wife. I received the ASC Fingerprint Notice on September 13th ( ASC Code 3) for both of us. Unfortunately my wife is out of the country and she will not be back till December 14th of 2009. Therefore I am planning to write a letter to the ASC asking to reschedule the appointment for both of us. Currently I am on H1 and my wife on H4 visa and have always maintained our status. I have several questions.
1. Since my wife is not here, Can I write a letter behalf of her to reschedule the appointment?
2. Do I have to send two letters or could I consolidate it as one?
3. What would you suggest I should do?
Thank you