Say "Cheese"

I am grateful to my old engineering buddy, JSF, for sending me this pic.
What the flying fruitbat does the photographer say to his subjects to get them into photogenic mode? "Say cheese?" "Smile?"
Assuming - and it is a fairly safe assumption - that the photographer is the husband of this quartet, how will he know, when he gets the photograph back, which of his darlings is which? Maybe it doesn't matter to him. Maybe, to adapt an old French proverb, La nuit, toutes les chattes sont grises. Given that "chatte", feminine form of "chat" ( "cat"), is also the slang word for a vital part of the female anatomy, he probably doesn't really give a f... f.... which cat he is stroking when the mood takes him.
I have a terrible feeling that this posting will earn me a fatwa. Well, there ya go, they always said that women would be my downfall.