Tandem tilt wing Elevons

Hello all,
I have a tandem tilt wing aircraft with elevons on the front and aft wing. My problem is the front wing is in front of the CG while the aft wing is aft of the CG. Therefore, in pitch the elevons must go opposite of one another but in roll they will got the same way. I can get pitch to work out but then roll goes opposite. Is there a simple way to add left and right elevon for wing1 and vise versa for wing 2?