USCIS confirmed that all I-140 petitions filed concurrently with an I-485 application for adjustment of status are to be filed with the Dallas Lockbox, unless the I-140 is accompanied by a request for premium processing, Form I-907. Concurrently filed applications that include a Form I-907 attached to the I-140 should be filed with the NSC or TSC, depending on the location of the petitioner.
I am a US citizen, had applied for my parents GC in October 2009. Mom underwent fingerprinting three times here, but did not get her AOS done in time. End of last year my father (who got his EAD and AOS smoothly) had emergency heary bypass here, and then they had to leave back for India for more tests. Mom left on AP. Subsequently I wrote a letter to NBC, MO to ask them to expedite my mothers case. Yesterday I received a letter stating that she has go to Philadelphia USCIS office next week for "Completion of application to register for Perm residence." Mom is in India now.
You need to contact USCIS customer service for guidance. Definitely put something down in writing that you are requesting a rescheduling. Maybe asking your Congressman's assistance is the best way to go for rescheduling.
Had a question about my I-485 approval and how to proceed forward with naturalization. Mr. Khanna was really helpful. After the consultation he let me ask follow up questions over the mail without any extra charge. Of various immigration attorneys I have spoken to over past five years, Mr. Khanna has been my favorite. Not only does he know the law but he cares about his clients.