Then make it like the pirate page which has 2 options that do different things (black market/pirate). I.e. On the left side of the old relations page, where all the race tabs are, put in a 'summary' tab, that pulls up the new relations screen. Ideally, put this at the top, and make it the default to display.
Alternatively, get rid of the old diplomacy screen, per se, and make it so when you click on a portrait in the relations page, the options for commands (trade/peace/pacts/etc) appear on a slide-out tray to the right of the race relations window. You can probably fit them vertically stacked, given the size of the relations window.
edit: pardon, I'm neglecting a few points. For either idea to work, you'd need to change the look-and-feel of the relations screen so that all relations are visible at once. For this, I'd take a page out of the Civ4 book, and just draw lines all over the place between the factions, and place them all in a circle... there is no need for our image to be prominent in the center. Next, make it so that when you click on a box, all but their relations dissapear. At the same time, this could be when their actions slide out to the right, if you like option 2. This would free up considerable space, since the tabs on the left of the relation screen wouldn't be necessary, but I don't know how much reworking of the code and existing visuals would be needed to circularlize the diagram, and make the pipes run to show all relations at once when necessary.
Overall, this is a UI problem, and there should be a way to combine them, but it would depend on the available effort and envisioned gains.
