Not entirely sure if this is the correct place to post this, and it might be a bit armchair game designer, but i have this idea that i think might be pretty nice.
The goal: Make you feel like you have some control over surrendering AI, regardless of whether you actually have control.
The "problem": The surrender mechanic is pretty cool and nice, I very much like it. However, I am sure everybody has a experience where a AI surrendered to "that guy", just before you captured that one planet you really wanted or not to you. If you look on any galciv forum i am sure you can find a example with some regularity. For whatever reason, it seems people are often unsatisfied with how a surrender plays out.
The Idea: Give the player a "not okay" button when a surrender happens, which has some effect. The effect can be anything, even nothing.
My ideal situation would be this:
You(first faction) are at war with a second faction, they want to surrender to a third faction.
A screen pops up for you that says: "Your enemy wants to surrender to Third Faction, are you okay with this?" yes/no
If you say Yes, the surrender proceeds as normal.
If you say No, Third Party gets a popup that says: "Second Faction wants to Surrender to you, First Faction is not okay with this, what do you want to do" accept surrender/decline surrender/negotioate.
If accept: Second faction surrenders to Third faction as normal, Faction one automatically declares war on Third Faction.
If decline: Second faction is forced to surrender to Player/First Faction.
If negotiate: standard diplomacy screen comes up that is basically a peace negotiation/threat of war. Third faction has to convince Faction one to be okay with the surrender by paying them off/threatening them/whathaveyou. If no agreeable trade can be made, it's war.
I feel like this would make surrenders feel much more interactive.