Slitherine

For USSR, USA, Italy and so on?
Italy enter war only after Germany's success in the West.
Other Axis sattelites also will not join Gitler before it.
Is it possible to join them after fall of Paris, for example?

Thanks in advance!

Not in the basic game - though ask the BJR modding team as they are doing some amazing stuff and may be able to do this sort of thing.