hey fate x i really really stress that you keep the babies to atleast 2,5 to 3 months old because in that time frame thats when they are gona have problems if they have any, some babies just die cause they wernt made to go any longer so just keep them for alil longer to make sure they have a good start so if anyone that is a new beginner wont kill it with in two or three days and you get alil more for them , right now they are ajusting to where you feed and water them soon as they learn that i would sell them then , im just tryin to teach yea to keep them to a good ripe ole age befor selling them cause if ppl come back sayin oh it died you look bad so just take a few mins and think about it , think about how they are gona do when they are 6 weeks compared to 12 weeks old , but hopefully you change your mind and become i really respectful breeder and good luck fate x , and for the flap under the neck its just some babies have it some dont just depends on how much fat they have lol