I-539 visitor visa extension - where to file and processing times

[msft]

I live in Maryland and am planning to apply for a visitor visa (B2) extension for my mom (her I-94 expires on March 28 and return ticket booked on March 26) and have some questions regarding the same.

 

1. Per this link: http://www.uscis.gov/i-539-addresses, if I go with the paper-based filing, I need to mail the completed form / supporting documents to the following Dallas address, correct?

 

USCIS Dallas Lockbox

 

U.S. Postal Service:
USCIS
P.O. Box 660166
Dallas, TX 75266

And not the VSC one:

 

USCIS Vermont Service Center
Attn: I-539
75 Lower Welden Street
St. Albans, VT 05479

 

2. The application processing time will depend on which USCIS office I mail my application to, correct? It looks like I-539 processing time at TSC is 2.5 months, while at VSC it's 5-6 months.

 

3. What happens to my mom's 10-year visa (going to expire in Dec-2016) if she overstays but leaves before the denial notice is sent/received by us?

 

4. If I file using USCIS Electronic Immigration System (USCIS ELIS), any idea which office will process the application: TSC or VSC or any other? Will the receipt tell which SC is processing it and the timeframe when the decision will be made?

 

5. From "Form M-752, Helpful Filing Tips for Form I-539" (http://www.uscis.gov/sites/default/files/files/form/m-752.pdf):

 

D. Submit a written statement that explains the following:

 

  1. The reason for your request to extend your stay.

 

Should my mom write & sign this letter herself or can I write one requesting an extension for my mom w/ the reasons and sign the letter myself? Also, is it ok to state that "the return flight ticket for the 'new return date' is not being booked without knowing the status of the extension request" or should I just reschedule the return ticket not worrying too much about approval/denial?

[t75]

Amy overstay could possibly affect future visas even if she leaves before receiving the denial.  Her travel history is hers for life.  It is recommended that you only request an extension for a very good reason.