I could be completely wrong, but I have always kinda assumed the pre-melt could be constructed in a way to feed multiple processors. So, in my vision, noting I have never been to the plant, I have been assuming 1 pre-melt and three processors, connected in a signle functioning unit.
But even if I am wrong, they have had multiple months now since the first pre-melt was built and testing so I would think, even if we needed a pre-melt constructed for each processor, those 2 additional pre-melts are already built.