USCIS announced that it has revised Form I-539, Application to Extend/Change Nonimmigrant Status, and that starting March 11, 2019, it will only accept the new version of the form. A new Form I-539A, also effective March 11, replaces the amendment pages normally used for children. (Parents or guardians may sign on behalf of children under 14 or any co-applicant who is not mentally competent to sign.)
The most significant change to the new form is the requirement that every co-applicant pay a biometrics fee and attend an ASC (Application Service Center) appointment, regardless of age. AILA has requested that USCIS delay implementation for 90 days, but as of late February, the new form and biometrics requirement remain in place.