I somehow did this a few years ago and I cannot remember how I did it:

If I need the original Package Studio project I do not have it anymore.
I somehow did this a few years ago and I cannot remember how I did it:

If I need the original Package Studio project I do not have it anymore.
Found the solution immediately after posting with the similar discussions recommendation. Just upload the updated APK file and it will add it to the package automatically. Wish that was more obvious. I am not sure how it knows to add that APK to the correct package.
https://pulse.soti.net/community/thread/f52b12ad-c95f-452f-af3c-5f2083e8bdaf
The answer to that is easy.
If you upload the apk as a package directly, the apk (bundleID) is the "package identifier" and the version of the app is taken as the package version.
So if you upload again the same app with different version, it just recognizes it on the bundleID where it belongs to.