void Funktion1(int i1, int i2, int i3)
{
...
}
void Funktion1(int i1, int i2)
{
   Funktion1(i1, i2, defaultwertfüri3);
}

public static void UseParams2(params object[] list)
    {
        for (int i = 0; i < list.Length; i++)
        {
            Console.Write(list[i] + " ");
        }
        Console.WriteLine();
    }

void myFunction(int a)
{
    int b = defaultB;
    int c = defaultC;
    myFunction(a, b, c)
}

void myFunction(int a, int b)
{
    int c = defaultC;
    myFunction(a, b, c)
}

void myFunction(int a, int b, int c)
{
    // mach was
}