I made a game with Quest. Is it possible to make it a library and then, when a user downloads it into his game file and sets it as an included library, everything I made will show?

NO, No it's not a game. It's something to help creators to make a Switch Character feature. If you want I'll post the game file here. All I want is it turned into a library(or guidelines to help me make it one).

You can make some UI elements appear by coding them as detailed here:
http://quest5.net/wiki/Editor_User_Interface_Elements

However, there is no option to simply have everything added to the object tree as though it were in their main game file.

I do a lot of fancy stuff in my library.

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