I've contacted Silvik (models originate from his mod) and asked about the ships. As their models are from another game and actually a property of Relic, no one can hold copyright for them. As for hardpoints and code, these things cannot be copyrighted within a Freelancer mod.
Therefore, as Silvik allows, we might also use those models.
Right now he is extracting more Homeworld models, and soon the collection of ships available in Mantaray's mod will probably increase. Inclusion of those ships into Discovery is scheduled for version 4.79, that will probably be released in 2-4 weeks from now.
P.S>Mantaray please use Caps when posting. Will make your posts more readable.