Some progress:
I did try the following definition:

typedef struct
{
int score;
STRING* score_char;
STRING* playername;

} our_player;

our_player our_players[10]; // define an array of the struct player

now this works:
str_cpy(current_player, our_players[i].playername); (in a for loop)
but this doesn't:
str_cpy(our_players[i].playername,current_player); (gives error invalid argument (string)

So if I could now find a way to copy the STRING current_player in the string of the structure my problem would be solved.

Any suggestion are greatly appriciated.
Gerrit