They aren't added on their own. propositions.
Parasolians: Castes have humans and elves with a very strong bias to dwarves. Castes are primarily for flavor, since they aren't playable. Ethics largely mirror vanilla dwarven, though with a somewhat lower regard for martial prowess and higher regard for rule of law and craftsmanship. Can trade for refinery schematics and alloy codices.
Description: A/An [Elf/Dwarf/Human] once in service of Parasol Industries, now trapped on Everoc peddling advanced industrial technology to get by. (Rogue version: This individual has turned to banditry and murder rather than science and industry to survive.)
BT Contractors: Castes have humans, elves, dwarves, and goblins. Slight bias to dwarves, very strong bias to humans (as humans formed the bulk of their Everoc taskforces.) Ethics mirror vanilla dwarven, with a maxed out regard for skill at arms and power over others (represents regard for chain of command and martial culture of the Contractors.) Weapons and Ballistic Armor codices are traded for from them.
Description: A/An [Elf/Dwarf/Human/Goblin] once in the employ of Ballpoint Technologies, now trapped on Everoc peddling advanced combat technology and hired muscle to get by. (Rogue version: This individual has turned to banditry and murder rather than honest mercenary work to survive.)
This way, we need to stay on good terms with both (at least initially,) to make the most of the tech lab and some other goodies, what with the idea being these are horridly expensive. Of course, we can also cheap out and purchase equally expensive pre-made suits of combat armor and considerably weaker (and cheaper,) coilrifles instead of making the things ourselves.
TRIPLE NINJA'D
@ Asea: We'll have to do the workaround route by making the codexes tools only their entities have normal access to (with an obscene value modifier for those items if possible.) As Nakeen said.