I am looking for an enhancement of the current page plugin. I need a solution where I can store a large quantity (1000+) in a treelike structure, add, modify, delete, rename, move a page at any position.

Presently the top is just a list of pages. Subpages can be arranange tree like, but once the page is added, there is no way to add a sibling before or after the current page. Is there any such plugin enhancement?