[X] Turn him in
Still the best option in my eyes.
Oku's advice is tinged by her inexperience and her bias against our brother. She sees every option beside killing Tet as bad, and unless you all think the QM gave us all Trap options but one, she is necessarily wrong.
Teo's advice is tinged by his bias towards our brother, whom he clearly cares for. Imprisoning him where we keep our secret formulae is a recipe for disaster. Having people we trust guard him implies we have people we trust, but we don't. Not personally, at least, though maybe Teo himself does, or thinks he does. Let's also remember the many hints about Tet having a lot of people loyal to him. There's a chance that some are among the people that Teo thinks he can trust.
He's against turning Tet in because:
1) "He has not yet committed a crime. I would not see him executed for this flight of fancy."
To which I say, I don't care. The intent was there. The planning was there. The lying was there.
2) "They will find other, lesser, offenses. Tax evasion for certain. Every clan gets a bit creative with their book keeping. There is every incentive to do so, and we must remain competitive. I doubt we can afford to pay our back taxes at the moment."
To which I say, first, tax evasion is terrible, and anyone who thinks otherwise, or thinks it's a necessary evil, or is proud to pull one over the government, or a dozen other reasons they use to justify to themselves the act of, in practice, theft, leeching, enforcing inequality, etc., is contradicted by any study in any field that ever focused on this matter.
Second, if we handle Turning him in right, which we should thanks to our resources and our high Persuasion, we might not have to worry about it, by making a deal, protecting ourselves/clan, getting an Imperial boon, etc.
3) "I suspect your mother has murdered people in the past."
To which I say, first, murder is bad.
Second, it's possible Teo is wrong about that.
Third, it's possible there is no evidence or way to prove it happened.
Fourth, if any murder happened at all, it was years if not decades ago, when mom had no position/title in the business.
Fifth, how would the Empire figure out a murder happened by auditing the clan?
Sixth, if it's by interrogating mom and divining/reading, and, for some peculiar reason about things completely unrelated to the business... then yeah, what can you do? Still, if the Empire was capable of such a thing without a possible way out of it, then how is this world not a utopia? And if there are limitations to what this method can do, wouldn't Mom, with her specialty being mental powers, be the best one to find how to exploit them?
[X] Airships