Las Meninas - donde están?

Las Meninas (1656) is a famous painting by Diego Velázquez.
And a mail art project (2015-2016) organized by Carlos Botana.

So far I always thought 'Las Meninas' was referring to the child in front, but when I searched for more information to create this mail art I learned that 'Meninas' means 'Maids-of-honour' (the junior attendants) and the child in the center is no 'menina' but the young Margarita Teresa.

Nevertheless, in my interpretation alas the Meninas have disappeared. The child and the painter himself (also pictured in the original painting!) remained.
As our present crown princess wears a pink dress on this stamp, I thought in those days Margarita might have liked a more prominent pink dress, too.




For the envelope I used some paper which showed an other painting by Velázquez, and a stamp showing the lighthouse of Terschelling, because it reminds me in some way of the lighthouse in the place of destination, A Coruña. And warm socks, it is winter now.
Finally, I could't resist to draw an artistamp on the back (here shown next to the front images) showing a Brazilian/Portuguese children's song: 'Vamos Menina' (aka 'Vamos Maninha'). I am curious to know if someone would have sung lullabies for la infanta Margarita in those days?