Hey @RafaZúñiga,
Hope you don't mind our reply in English. We're happy to answer that question for you!
When you accept a Premium for Family invitation, your current subscription will be canceled. You don't need to do this manually. So no worries, no extra charges 🙂
Hope that explains it! If there's anything else we can do for you, let us know.
Have a wonderful day 🙂