As necklines are the only thing I'm probably good at I'll use its technic :-)
I've sewn this piece of fabric to the upper end of the future gore. After sewing I cut it in the middle and turned it to the wrong side. Then I've added the whole gore (without the pike). Now I can use the hidden backstitch to attach the gore to the upper ply and maybe once rip out the middle auxiliary one.
Why does it always have to be so complicated:-)