My generation

Looking through family photos recently, I came across one that surprised and intrigued me.
My mother was one of three children (Iris, Jean and Allan) all of whom had children: 4, 3, and 4 respectively, which makes 11 grandchildren in total.
Now, Allan's family lived in Dunedin, we lived in Wellington, and Jean's family lived in a number of places in the South Island, so, although we had contact we didn't ALL get together at one time and place.
Except once, as the photo below attests.

Those shown are (the numbers represent their position in the three families):
L to R: Ron (1.2), Bryan (1.4), Elisabeth(3.3), Robert (2.3), Craig (3.4), Tony (3.2), Kay (2.2), Graham (3.1), Barbara (1.3), Ian (2.1), Louise (1.1).
As far as I know that is the only such group photo in existence.