Originally Posted by
Marambio
Actually there are four lines: Argentinos, Mercosur, rest of the world and USA/Canada/Australia, which are the three countries that have to pay the reciprocity fee. Your daughter should follow the signs for the latter.
She shouldn't worry about customs. They hardly check foreigners.
"They" don't know if you are a foreigner or not while looking at the X-ray screen, so unless they've seen you holding your non-Argentina passport beforehand, or look at you holding it afterward, you could be from anywhere, as the customs lanes are not segregated.