How to add custom field CiviCRM to allow user buy a ticket for multiple events?

Question

I'm editing my question to make more clear.

User Case I want to publish an event where the user is able to choose specific package from for the ticket.

I also want to allow my customer to choose a ticket that will allow them to attend more than 1 event.

How can I do this using CiviCRM?

Idea 1: One of my idea is to add a hidden field in the form that will be filled up using javascript if the user choose the ticket for multiple events but I don't want to do this because I want to allow the admin to specify this value when creating the event in the back end.

Idea 2: I am trying to add custom option in the price field when creating the price set so that I can add the number of extra event that I to provide to my customer. So how can I add this? Is this the ideal way of using CiviCRM?

Or is there another way to do this? I've been at this for almost a week but no solution.

I really appreciate any suggestion. Thank you.