回複：父母B2簽證延期

if you read the instruction of form I-539, you will find you really need u parents' original I-94. But i guess copy of I-94 is fine as well. I renewed them both for my parents and my parent-in-law and always ted original I-94. Both of renewal were approved.But the first time the original I-94 didn't return to us. The second time the original I-94 returned to us together with approved renewed I-94. Good luck!