Eurgh

Why don't we just play it out?
Everyone has their own ship classes, but when/if (More likely if) a sort of United Nations is formed, then they can go and vote or whatever on various propositions and bills. For example, a couple nations could communicate, draft up a firm galactic standards for ships, and then propose it in the Galactic Conference or whatever, where all the nations can say yay or nay, and then if it passes, the spacey-UN can enforce it among its member nations and try to put it on outside nations. 

It's also quite possible that if my nation were to be in such a UN of sorts, other nations could draft up a no-slaves no-indenturedservants proposal, pass it, and then my nation would be forced to give up significant industrial power and economic efficiency, to 'free' and establish rights and fairer quarters/treatment for the former slaves. Then my own nation would be at a political disadvantage, because those alien races would still be under the Hocklyn flag, but could wield political power, and would probably outnumber Hocklyns as a whole, and take political, economical, and industrial power within the nation.