TSA does not screen passengers getting on international flights in foreign countries. Anyone coming in has to get through customs. Many food items are prohibited. I would hope they are not letting in poultry eggs from locations that have known illnesses such as AI, Newcastle, etc.
Given that mail shipped eggs are subject to quarantine and require a lot of paperwork I doubt you can just carry hatching eggs into the US on a flight and be on your way. I can't find any info on the APHIS site about this scenario so your best bet would be to call and ask. At a minimum I expect...
More information is needed. First suspect would be coccidiosis.
Were you giving them medicated feed? How old are they? Where did the chicks come from? What does your brooder setup look like? What are you using for a heater?
Sexed silkies are only offered by My Pet Chicken. Those that have reported here on MPCs bantam sexing have said they have been accurate.
However it will cost you. MPCs straight run silkies are $6.50. Sexed pullets are an additional $22. If you are getting a small order on top of that the...
Pullets nearing laying age, as well as new layers are often cranky due to hormones. Add the usual nightly roost scuffle along with a small coop so it isn't too surprising to find some that want to perch outside. What is the cockerel doing? Is he chasing some of them from the coop?
I've had a fox take a half dozen birds with almost no trace. I've also had birds that have had a close call with something and are too afraid to move even though the sun is setting. Hopefully they will pop up in the morning.