Using "once upon a time" in a present tense sentence?

I work in a company that sells simple children's books. A customer complained that the book changes tense randomly, and they're right. This book was created years ago and needs updating to ensure it uses correct grammar.

The book starts out like this:

Once upon a time in a faraway land, Princess $Name$ lived in a
beautiful castle atop a high hill. She had a very busy schedule, each
day slightly different from the last.

That's fine, however on all subsequent pages, the text is written in present tense, like so:

On this particular morning, Princess $Name$ awakens to the sound of a
songbird singing outside her window.

The story is designed to work in present tense, so rewriting from present tense to past tense is not an option. I'd like to rewrite the first page so it's also in present tense, but I'm not sure how.

Does it make sense to use "once upon a time" in present tense? For instance:

Once upon a time in a faraway land, Princess $Name$ lives in a
beautiful castle atop a high hill. She has a very busy schedule, each
day slightly different from the last.

But that reads weirdly to me. Alternatively, if that doesn't work grammatically, is there another way to write "once upon a time" such that it sounds ok in a present tense sentence?

Answer

I don't think "Once upon a time" can work with the present tense. There's no present tense equivalent.

Why not start,

In a faraway land, in a beautiful palace atop a high hill [there]
lives a princess. Princess $Name$?

Or you could use the Middle Eastern "There is, there is not", though that too is usually in the past tense.