A population half to two thirds as big as our own is too big for us to easily integrate, so neither coequal alliance nor subjugation is ideal. In the first case, we will have a direct competitor, if a peaceful one, who we may eventually unite with after many generations, but who will for the practical duration of the game be an unreliable and culturally dissonant partner with its own identity and therefore its own goals. In the second, we will have to spend a considerable part of our resources to keep them under control, since their desire for independence is already proven.
I wish to bring them into a subsidiary partnership which will eventually dissolve and consume them as a separate nation. Therefore, we should divide them, like the Sabines, allowing them progressively to integrate into our culture over time. The recipe for doing so is well-established by history.
I propose the following unequal alliance:
1) Our established merchants and tradesmen will have free rights to operate and domicile in Ewadd, while maintaining communication with Gedur and a right to preserve their Gedurian cultural practices in Ewadd. Should they grow in number, a specific portion of the city will be allocated to them as a cultural quarter. Should they so choose, they will have the right to take Ewaddian wives, and bring them back to Gedur when they return. They will also have the right to bring Gedurian apprentices to Ewadd or take Ewaddian apprentices (being encouraged to instruct the latter on Gedurian culture); "graduated" Ewaddian apprentices who are vouched for by Gedurian masters will be permitted to settle in Gedur as well. Gedurian merchants and tradesmen in Ewadd will be granted equivalent trade rights in the Gedurian market to those living in Gedur itself, so they will have the economic advantage in Ewadd.
2) Ewaddian youth will have the right to join the Gedurian army to make their fortune, and, should they comport themselves with dignity and courage in a manner becoming of a Gedurian soldier, will be permitted to settle in Gedur after their term of service. As Ewadd presently lacks an army, we will magnanimously take over the question of their defense with our own so there is no need for them to raise a separate army, and they are instead encouraged to join ours. Of course, Gedurian culture will be enforced (with a light hand at least at first) in the ranks and integration thereto will be a condition of promotion.
3) Those of the Ewaddian landed elite who wish to live under the splendor of Gedurian culture will have the right to migrate to Gedur upon payment of a modest fee. Unlike our own migrants in Ewadd, we will distribute them throughout the city without allowing them to concentrate in any particular area, and the fee will be calibrated from time to time in order to limit them to a minority of less than a third or so of our own native elite. They will be encouraged to adopt Gedurian culture, their children will be permitted (that is to say, strongly encouraged) to marry into the Gedurian native elite, and, of course, Gedurian families will be allowed to inherit from Ewaddian ancestors.
4) Members of the Gedurian landed elite, including those of Ewaddian descent, will have the right to be received in the Ewaddian court, should they visit Ewadd for any reason, with the pomp due to their station. Of course the same right will be extended to Ewaddians in Gedur, but, as we are a larger and therefore ostensibly grander city, we will implicitly expect more pomp for our own elite than the reverse. Should this prove a drain on the Ewaddian treasury, our own merchants and tradesmen operating in Ewadd will be happy to offer reasonable loans, I am sure.
5) Ewaddian maidens will have the right to come to Gedur seeking Gedurian husbands. This will naturally be necessary since a proportion of Ewaddian young men were removed by way of point 2. Gedurian men will have to pay a small fee for permission to marry Ewaddian women, which will be calibrated from time to time to keep the level of Ewaddian immigration low; and the fee will be reduced for men who already have Gedurian wives, provided they have more Gedurian than Ewaddian. Ewaddian men living in Gedur due to any of the other items in the list will not be permitted to bring in new Ewaddian wives in this (or any) way, barring exceptional circumstances, but will of course be encouraged to marry any good Gedurian girls who will have them.
6) Needless to say, all Ewaddian immigrants in Gedur will be encouraged to adopt Gedurian culture and pass it to their children, and their children will be encouraged to marry full-blooded Gedurians and disseminate through Gedur rather than concentrating anywhere as an ethnic minority. Anyone of fully Ewaddian ancestry maintaining Ewaddian culture will also not be permitted to own Gedurian land, although, since the landed elite ought to be quite small in this time period, I don't expect this to come up at all anyway. All residents of Gedur will be encouraged to think of themselves as Gedurians, as will all Gedurians in Ewadd.
7) In no circumstance should Ewaddian immigrants to Gedur be allowed to outnumber Gedurian emigrants to Ewadd. We should maintain a flexible target of about half as many. All migrants on both sides will be guaranteed the full rights and franchise permitted to citizens of their town of domicile.
8) From time to time, Gedur may choose to make investments in Ewadd for the good of both peoples - perhaps building granaries, or new walls, or mills, or what have you. Such investments will be understood to remain Gedurian property, with any fees for their use, etc., being due to the Gedurian crown; after all, we must be free to act in the interest of our shared prosperity.
Matters pertaining to our internal policy, like the encouragement of cultural assimilation, though, the Ewaddian delegation don't need to know about. They should only be told about what their own people's rights and ours will be under the new system.
In this way, the flow of Gedurians into Ewadd will be made up of the affluent and established who are more likely to maintain Gedurian culture, serve as Gedurian cultural ambassadors to Ewadd, and gain political influence in support of Gedurian interest, while the flow of Ewaddians into Gedur will largely be the young and impressionable placed in a position of implicit subjection, as well as that portion of the elite willing to subject themselves to whatever Gedurian court grandeur may be. (Hopefully it is better than Ewaddian.) The overall effect is to position Gedur as the superior city culturally, militarily, and economically, so the influence will flow from us to them and whatever conservative remnant in Ewadd resists Gedurization can increasingly be marginalized over time. In time, if we can make ourselves impressive enough, even the full-blooded Ewaddian youth living in Ewadd would come to see themselves as Gedurian, and avenues for their integration into Gedur should be expanded - as long as avenues for Gedurian settlement in Ewadd are also expanded.
In principle, Ewaddians are offered quite a lot of privileges by this plan, so unless they are far-sighted enough to perceive the implied extinction of their culture, it seems unlikely that they would reject it. It technically includes their full demands - Ewaddian "independence" and Gedurian military support - and can even be sealed with a marriage if there is a good available candidate. But in time, it entails their complete subjugation. I assert this proposal to be option E, for Ewaddia delenda est.
Also, I think it's just a lot more narratively interesting.