This is a thought, not tested, don't know if it's possible.
As we all should know, if you're playing as the ruler of a republic, you get a +1 trade post bonus for adult male family members in court. Now, let's say you're the ruler of a republic, and your brother is scheming to do whatever, doesn't matter. You imprison and enslave him. Now you force him to breed. Ah, but all the children will be born bastards, and thus not part of your dynasty! Well, let's say you married him to a woman that you knew was plotting to do whatever. You imprison and enslave her too. You force him to breed with his wife, and the children presumably are a part of your dynasty and when mature, give you the plus one trade post bonus. Repeat until your court is full of adult male family members.
I haven't checked this out myself, has anyone? Can anybody tell me if this is doable? I like playing as a republic but only if I make an absurd amount of money.