han or hayan reservado

Question

Let us imagine the following scenario. There is a crowd of people at a cinema. what would the ticket controller use to invite those who had bought tickets in advance. haya or han comprado/reservado?

Answer

Hola Emanuel
The ticket person would most probably say:

Aquellos que hayan comprado tickets por anticipado, por favor, pasen por aquí.
(Those who bought tickets in advance, please, come this way.)

The subjunctive is most likely to be used because the ticket person doesn't know for sure if there are actually people who have bought tickets in advance. There might be some, there might be no one.
However, if the ticket person knows for sure that among the crowd there are (or most probably there are) some people who have bought tickets in advance, then he'd say:

Aquellos que han comprado tickets por anticipado, por favor, pasen por aquí.
(Those who bought tickets in advance, please, come this way.)

So it all depends on the certainty or uncertainty of whoever is speaking.
But we do have a lesson on these clauses that use the indicative and the subjunctive. One of our examples is precisely this one. Here is the lesson.
Saludos
Inma