A caja mixta is how an Argentine buys pastries for other people: you do not pick one flavour, you take a box and let the table sort itself out. Plain medialunas de manteca alongside the filled ones, in a single box.
It is also the honest answer to “which should I try?”. Most people find out they are a dulce de leche household or a plain household by eating both in the same sitting.
If you want the box weighted a particular way, say so in the order notes at checkout. For a room rather than a table, catering is the better starting point, and the guide to party and office orders has the quantities. How ordering works covers collection and delivery.





