Hello, I am trying to extend my mother-in-law's B2 visa. She has got two passports. Old passport is expiring in 01/08/2019. New Passport expires in 07/10/2028. She arrived here on 08/01/2018. Her I94 was issued on the old passport. But expiry on the I94 is still 01/30/2019. while trying to fill in I-539 document, I have to provide I-94 information. Which passport number should I give in the 11.b. question?. If it is old passport than how should I add an addendum to I-539 to include new passport information. I couldn't find any addendum document in USCIS website.

User's Location: Rancho Cordova, California, United States of America

Category: B2 Visa (Visitor Visa)