How can I dynamically load and open tree from bottom/leafs?

[FredrikElliot]

I have a functional tree that loads properly using ajax call in core.data when initialized.
I have a list of leaf ids that I need to open and select. Since the tree contains thousands of leafs, I don't want to load the full tree, but only the paths to the leafs in the list of ids. How can I do that? Is there an automatic way to include the loading of a not-already-loaded parent of a leaf I want to load?

I'm using load_node for the nodes and currently looping up to the root node for every leaf and adding all ids to a list, which I load in reverse order. But for many leafs the paths combine somewhere and loading all these already loaded parent nodes is inefficient. How can I do this smart?

The ajax call includes both child and parent id.