adding two phone agendas toghether

I got this problem where I need to create a phone agenda where every name coresponds to a phone number. I decided to create this as a bidimensional string array. But what I do not know how to do is: I need to create 2 agendas(created in main) and then add them toghether to create one big agenda that contains the members of ag1 and ag2. Please help me create the method that does that.

#include "stdafx.h"

using namespace std;

class Agenda{
    string date[20][20];
public:
    Agenda();
    void afisare();
};

Agenda::Agenda(){
    int i, j, n;

    cout << "Numarul de intrari: ";
    cin >> n;

    for (i = 0; i < n; i++){
        for (j = 0; j < 2; j++){
            cout << "Date[" << i << "][" << j << "] = ";
            fflush(stdin);
            getline(cin, date[i][j]);
        }
        cout << endl;
    }

}

void Agenda::afisare(){
    int i, j;

    for (i = 0; i < 2; i++){
        for (j = 0; j < 2; j++){
            cout << "Date[" << i << "][" << j << "] = ";
            cout << date[i][j] << endl;
        }
        cout << endl;
    }
}

void main(){
    Agenda ag1;
    cout << "-----AGENDA 1-----" << endl;
    ag1.afisare();

    Agenda ag2;
    cout << "-----AGENDA 2-----" << endl;
    ag2.afisare();
}