HELP DAY 19!! Cracks in air cell part of shell

[RMRChickens]

Please help!! We live in california and its been 60 degrees during the day and 40's at night and have a hen splash cochin hen on day 19 sitting on eggs and noticed one of the eggs has mulitple small cracks on the air cell side.. I thing she somehow accidentally cracked it because none of the other hens can get to her she is by herself. I candled it today and saw veins and the chick moving and alive with no internal pip yet.. This egg is very special as its the only one we have from my daughters favorite chicken that was killed by a fox 2 weeks ago. I want to do the best i can to make sure it survives!! Should i be worried ,or do you think i will have to help it at all, or what problems can i encounter or what should i do or not to do or just leave it alone at this point since it shouldnt be moved anymore. If it makes it , it will be a frizzled easter egger crossed with our salmon favorell rooster.
Thankyou for anyones help!!!

 

[My15Ducks]

I put candle wax on my cracked hatching eggs. Just a little wax right on the crack. I’ve heard that unscented wax is what you should use. So far my cracked egg is thriving. But maybe because your egg is so far along it will be ok.
Good luck!