Have the ability to save/load a named treaty, with all it's customized items. So they don't have to be re-invented every game.
First contact? Just load up your carefully designed "First Contact Scenario" treaty proposal. Or maybe you have a couple paths in mind: First Contact - Probable Enemy, First Contact - Probable Ally.
Who cares what shipset you're playing with right now? That's not going to change the treaties you want to load.
Same with ship designs. SE3 did this right with its saved designs being completely independent.
Well, if you always RP a particular personality for each shipset, it might come in handy; aggressive, warlike empires don't really have much use for the "Daisy Flower" trade ship now do they?
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O'Neill: I have something I want to confess you. The name's not Kirk. It's Skywalker. Luke Skywalker. -Stargate SG1