It seems that if you are upgrading to Edge, you need to do multiple phone separately.
After finally getting into the checkout process with 2 phones, they were showing up full price and the Edge option never appeared. I did this a couple times before doing it separately and then it worked correctly.
This happened to me too when I ordered my phone. I ordered the iPhone 6+--64GB/Space Gray--for myself and an iPhone 6 for my father--16GB/Space Gray--and had to go back in afterwards again to do the second Edge for his line.
I did mine first. After numerous errors like you spoke of (iPhone appearing at full price and no Edge being offered). It finally offered edge, said Sept 19 for the Plus, and then when I was finally to confirm my purchase and order it was bumped to 10/7. Hopefully this is not the actual shipping date and maybe a glitch (fingers crossed). My fathers is arriving the 19th, thankfully.
Anyone know in the past if the leadtime has been shortened at pre-order when it's estimated a couple of weeks after the first day of deliveries?