Displaying a subcategory's siblings on a page

[matthewshea]

My site has categories and subcategories.

When you click on a category, that category's child categories are displayed.
When you click on the sub-category, the other sub-categories disappear.
Is there a way to get the sub-categories to stay visible using the templates? Or is there a function I can call to get the parent (top level) category, and from there get the sub-categories?

The client wants all sub-categories to be visible, with the currently selected sub-category highlighted.

[Jamie]

By default, the Product Catalog navigation block will show the open top level category, and all subcategories below it regardless of which subcategory you are currently viewing:
example.png

[matthewshea]

Thanks Jamie. I split the Category parent and children into separate blocks. That probably has a lot to do with it. I'll post what I did wrong as soon as I figure it out.

Matt