It's hard or even impossible to cover everything in Kingmaker especially if you mix and match your party.
Yeah I already covered this in a post right near the beginning of the thread which you obviously didn't bother to read. There are multiple characters who receive 5 or 6 points to spend on level up, let alone if you make your own character a skill monkey. Yes, you will be unoptimal in the sense that you may be missing a +3 from it being a class skill or something like that, but it will be more than enough to cover the vast majority of checks in dialogue, with most of the failures coming from rolling a 2 instead of being statistically unequipped to deal with them. Octavia can cover Mobility, Trickery, Stealth and Knowledge: Arcana by design. She needs these skills to spec into Arcane Trickster, and the Necklace of Double Crosses (which provides a +4 to the first three) is basically made for her. You then have a point leftover to put into Knowledge: World.
Jaethal covers Athletics, Lore: Religion, Persuasion and Perception by design. You then have an extra point to put into Lore: Nature if you're so inclined, since using magical items, while useful, never comes up in dialogue as far as I know. I'm pretty sure both of these characters receive the class bonus for everything listed here, too, since I am almost certain that every skill counts as a class skill for them. Jaethal arguably isn't optimal as a face, since she only has 14 CHA and the player probably wants to boost her Wisdom for spellcasting purposes. Thankfully, there are four other characters left to cover that problem, and the player can easily be a "charisma tank" of absurd proportions by playing something like a Sorcerer or Paladin.
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