This would pose some focusing and point of aim point of impact shifts in this configuartion. A few folk have tried this with a few ACOGS with the same result. Your best bet is to place the NVD behind the day optic. Hope this helps.
Edited to add...The only device which you CAN use a NVD in front of a day optic is the UNS or PVS-22 that us made expecially to mount in front. At 8k or higher, they are mission specific pieces of gear.