deleting and adding leagues

My next task with this great game is to work on completing as many challenges from the Steam list as I can. I noticed there are 6 challenges where I am needing to take a club from the lowest league in a country and get them to the top league in the country. Along with those 6 challenges, I know there are a couple national challenges, such as being offered a management position with a national team. What I would like to do is combine these things. For instance, right now I am playing with a team in the lowest Spanish league, after I get them to the top, I want to delete that as a playable nation and add the next nation as a playable league. (I believe the challenges are for Spain, France, Brazil, Italy, Scotland, and England.) I don't want to start a new game every time. I would like to have a long running game in which I also manage a national team.

Does everybody understand what I'm saying? Is it possible to delete one nation as a playable nation or league and then to add another league as playable? Please let me know if I can do this or if I need to start a new game for each challenge?

no you can do this you can use the add or remove leagues feature, for example you could start with england, then add in spain, then remove england ect...

Yes, I understand you. You can do that, however I would not recommend adding leagues on FM 12 (If that's what you're using), as it would slow down/ruin your game completely due to a serious problem. I'd suggest starting the game with any many countries as possible, and gradually removing them over time.