I haven't been able to figure out how to add players to national teams. Does anyone have a suggestion?

I don't know if this will work...I never tried it. However, you might wanna try using FEd99 by copying a player from any team, and pasting him into the team that you want to update, change his attributes, name, blah blah...you see where I'm getting at right!?

Greetings from Batigol.

Batistuta is right. Use FEd 99 to copy and paste a player onto the national team. Just remember, when moving players this way using FEd 99, when you make changes to the player you pasted onto the national team, those same changes will take affect to the player you copied on his original team. For example, if you copy Massimo Ambrosini from AC Milan and add him to the Italian National team, then change his position and number for Italy, those same changes will take place on AC Milan. The way to get around this is after making all the changes you can with FEd 99, use the ingame editor to make independant changes for the player at each team.