Reply to S4 with 4 Effect Units Help

Hi, i'm really a newbie to all that mapping and so, but i decided to give a try today. I have a S4 and a Korg NanoKontrol, and i want to use the NanoKontrol, to control effect unit 3 and 4. As you proberbly know, when you switch to 4 effect units mode, you can only assign unit 1+3 to the left decks, and 2+4 to the right. So my question is: Is there any way to assign all units to deck A + B, and then just control effect unit 3+4 with my NanoKontrol?