I couldn't email you via your comment so I'm letting you know how I did my Aidez neck on my blog - who knows...maybe it will help someon else!?
I knit the neck bit for the 3 3/4 as it told me to...when you get to that point see if you can gently stretch it to reach the center of the neck. If it works then you are good. Do not make it the full length to get to the center of the neck as I don't think it will set well...it will bunch. When seaming you just need to put the two neck ends together and then ease the fullness of the body to what neck you have knitted.
I hope this helps!