Rohr94 is right. I think people try to read too much into the rules. Example, the minor axis IC’s. Before there were no IC’s but they could still produce units. Then people asked about building naval units. Just build a naval base and then build a ship!! Lol. On setup there are some countries that dont have naval bases and IC’s in the same zone……so what! That just means in order for them to build more naval units they would have to buy and place an IC and naval base in the same zone.
You shouldnt put 2 ic’s in the same zone, although there is no rule against. That is why the minor axis had special IC rules.
If you capture an IC, that is from the enemy, it is reduced in power or production. So if the IC in Paris is under axis control and it is a minor then the capturing of the IC would destroy it. Also I thinkb there is nothing in the rules about capturing a major IC, it becoming a minor IC, but later upgrading it back to a major IC.