Well, first of all, thank you all who taught me how to optimize my specialists in the cities to get ahead of the AI in science
it turned out great, I'm not only leading in science, but also number 1 in everything in the demographics screen, with 60 happiness, even though everybody in the game is guarded against me and refusing to trade. I guess a few more games and i will be ready for emperor! Of the 20 CS, 19 are my allies, I hardly lost a quest since the renaissance... Thing is, I adopted freedom and everyone else order / autocracy. Apparently there was a civil war in Russia and one of her cities joined my empire.
And here comes my question. This city is located between Moscow and the 20th CS, which I never got a chance to be allied with because it was conquered by Cathy early in the game. I'm sending a few units to the new city and trying to figure out a way to liberate the CS. Should I attack Moscow, kill a few Russian units on my artillerys range and ask for the CS in a peace negotiation then liberate it or should I attack the CS, conquer and then liberate? I never tried to liberate a CS before, so sorry if my question sounds stupid.

And here comes my question. This city is located between Moscow and the 20th CS, which I never got a chance to be allied with because it was conquered by Cathy early in the game. I'm sending a few units to the new city and trying to figure out a way to liberate the CS. Should I attack Moscow, kill a few Russian units on my artillerys range and ask for the CS in a peace negotiation then liberate it or should I attack the CS, conquer and then liberate? I never tried to liberate a CS before, so sorry if my question sounds stupid.