Hiding a tree widget will hide the entire tree and all of its nodes at once, so what you could try instead is to create your own custom tree widget using groups or dynamic panels. This would involve using "push" and "pull" interactions, which push or pull elements underneath a widget whenever it's hidden or shown. If you're not yet familiar with this approach, I'd recommend checking out this tutorial on our support page:
You can also read more about Axure RP's push/pull interactions here:
Using this method, you'll be able to create your own custom tree widget and hide/show specific sections of it as you'd like. Let me know if you have any questions about any of this!