does this add the second user to the friend's list of first user?
if ((first_user->friends[9] != NULL) && (second_user->friends[9] != NULL)){
             for (int i = 0; i < 9; i++){
                if((strcmp(first_user->friends[i]->name, second_user->name)==0) && (first_user->friends[i] != NULL)){
                    if (error < 1){
                        error = 1;
                    } 
                }
                else{
                    // add to each friend's lst
                    int stop1 = 0;
                    if (stop1 == 0){
                        first_user->friends[i] = second_user;
                        stop1 = 1;
                        error = 0;
                    }
                    
                }       
            }
}