I WOULD LEAVE THEM JUST IN CASE BUT U SHOULD BE ABLE TO TEL BY LISTENING OR BY THE FEEL IN UR HAND IF BIRD IS DEAD IN SHELL THE EGG WILL SEEM TO ROLL ABOUT IN UIR HAND IF OK WILL LIE FIRM, THIS IS SOMETHING WHICH COMES WITH EXPERIENCE, BUT BREEDING EARLY GIVES U THESE PROBLEMS EGGS GETTING CHILLED WITH ALL THIS COLD WEATHER, AS I WRITE THIS WE HAVE ABOUT 6-7INS OF SNOW AND STILL FALLING, NOT NATURAL FOR BIRDS BREEDING IS IT, THEY ARE MADE TO BREED IN THE SPRING, 21 DAYS IS WORTH ANOTHER 2-3, IF NOT LIFT THEM, MAYBE U GOT UR DATES WRON IN LAYING, BUT U SHOULD BE ABLE TO TELL BY THE EGGS