Well shipped eggs get jostled around a lot. There are temperature extremes as well. You never know how old they are or what conditions they come from, and even for that matter if they are pure bred. An average of 50% hatch on shipped eggs is good, where as at home you can expect between 80 -100 % easily. I would attribute poor chick health more to diet of the hen than due to the shipping, since they did hatch fairly decent. Also when you get specialized colors like the lavenders, the roosters and hens might all be related. That also causes chick deaths. Nature has a way of weeding out problems like that. That is why I try to change a rooster or a blood line at least every year or two to avoid too much inbreeding. I am thinking since these came from the same place inbreeding might be more of a problem. I have some more unrelated eggs in the incubator and haven't checked to see if they are developing. There isn't many of them but maybe I will hatch a few out of them. You can ask questions all day long when buying hatching eggs on line but people are only going to tell you what they want you to hear for the most part, so there is no way to know exactly what you are getting.