Hey Pg28,
I'm in the same boat. Did you get any concrete information on that ?
I'm not sure either about the correct filing fees ? Few say that irrespective of paper filing or e-filing one has to pay the fee amount of $370 + $85 ( X2) = 910. Reason that I read online and from well wishers is that B-2's extension of stay have no such thing that covers the one fee ($370) for 2 applications. However, $85 biometerics fee is must for both.
Let me know if you have got any information on this, so I could file accordingly. Have a good day!
-Sj8