I have always played on a large map. Finally I am now playing a huge map with 16 civs. I noticed the remaining 8 civs don't show on foreign advisor screen or is there something I am not aware of? This huge map is fun but I think I might prefer large maps most of the time.
Press Shift and right-click on one of the leaders in the Foreign Advisor screen, and you'll be able to select which civ should show up in that spot. Note that three-way agreements (military alliance, trade embargo) only show up if all three civs are shown on the screen.