Problem Setting Default Apps

[Dreamspinner3]

I am trying to set the default app for .pkg (package) files for the Sims 4, but can't find a way to do it. If I go into choose default apps by file type, .pkg files don't show up on the list! If I choose set defaults by app, the app I want to set as the default for .pkg files doesn't show up. How do I get around this issue? Help!

 

[T Moore]

You do not open the file. All you have to do is get in the correct folder.
Game Help:Installing Sims 4 Package Files - SimsWiki

 

[Dreamspinner3]

Okay, but I still should be able to use a third party app, in this case Sims 4 Studio, to open them and set it as a default, shouldn't I?