Okay so I think you explained it already but I'm still confused. Chronologically, which trolls were first and who grew up to be the ancestors (like Mindfang)?
Karkat’s group were created first and then their genetic material was mixed to create Meenah’s group. Post-scratch on Alternia it was Meenah’s group who grew up to be the ancestors. That’s why Vriska called Aranea a “dorky teen mindfang”.