Great, then. I was thinking of taking the managerial job at some former French colony and start to call some players, but since I've never tried country management I wasn't sure
No one has actually answered your question though :S I don't think you can call them up if they have been declared. Not sure though I think it depends if they want to play or not.
you can call up any player no matter if they are declared or not but they have to be Elegible to play for the 2nd nation as well...
you have a better chance of calling a player up if they are not declared for the 1st National team...
as Robshkii mentioned above, you may find it difficult...