Well, I'm sorry but you're wrong.
First of all, Yamato is considered to be a small to medium player on the hi-end toy market. Bandai is the toy giant.
Second, a mold can not be modified to create a new toy. Creating a mold is a very very expensive process so you don't just modify it to make a slightly different toy, because you wouldnt be able to use it anymore for the original toy you created it for.
Third, the two-seater VF's can't all be created from one mold. The VF-1D and Elint Seeker, for example, are two completely different VF's, sure, they're both two-seaters, but that's about the only feature they share.
The only "official" confirmation we've had regarding 1/48 two seaters is from Graham stating Yamato won't produce any.