A lot of big breeders seem to cut them all at least by the time the first pips and get along just fine. Heck, it seems they sometimes cut them all way early just to see what is there and apparently get away with it. I think there is a special technique you can use where you pinch up a place on the top and work the membrane down so that you only cut the shell and not veins but I'm not expert. I'd wait till morning and see if the last couple don't cut their own way out.
I saw where with another species someone actually incubated a split egg successfully so apparently they can be tougher than you think.