Started with 7, down to 3?

[Bnemeth]

I had 7 call duck eggs in the bator for lock down and today is day 27 - one pipped last night around 9pm and is slowly working his way out. The others haven't pipped and when I candled them 4 looked "weird" and did not have solid shadows so I broke them open. Three looked like they were shrink wrapped but there was fluid under the membrane and the 4th didnt looks wrapped but had a lot of gel like fluid under the membrane - any idea what happened to these eggs? I could see veins on the other two so I put them back in the bator - will those ones hatch? Should I break through the shell into the air cell? Any help is greatly appreciated, thanks!