Java - JTree, DefaultModelTree won't update

Question

Is it possible to add nodes just before expanding a tree, no matter how I approach this it just doesn't work at all. I've used all of the DefaultTreeModel's functions and it just doesn't seem to work, am I missing something or do I need to find another way around this?

public class Test {
    public static void createChildren(FileNode pNode, DefaultTreeModel pModel) {
        createChildren(pNode, pModel, 0);
    }
    
    public static void createChildren(FileNode pNode, DefaultTreeModel pModel, int pLayer) {
        // if node doesn't exist
        if (pNode == null) {
            return;
        }
        // Get the root
        File root = pNode.getFile();
        File[] inDirectory;
        
        // if we aren't in a directory or file doesn't exist
        if (!root.isDirectory() || !root.exists()) {
            return;
        }
        
        // List files in directory
        inDirectory = root.listFiles();
        // If there are no files, do not bother
        if (inDirectory == null || !(inDirectory.length > 0)) {
            return;
        }
        
        // If the node has children replace
        if (pNode.getChildCount() > 0) {
            // Delete ALL Nodes
            deleteChildren(pNode, pModel);
        }
        
        // Then we will create the children
        int[] inds = new int[inDirectory.length];
        
        // i scales for ALL FILES, Index scales for DIRECTORIES ONLY
        int index = 0;
        
        for (File f : inDirectory) {
            // Create a new child
            FileNode child = new FileNode(f);
            // Add nodes if we are in the layer to do so
            if (pLayer < 99) {
                createChildren(child, pModel, pLayer + 1);
            }
            // Add the node
            if (pModel == null) {
                pNode.add(child);
            } else {
                pModel.insertNodeInto(child, pNode, pNode.getChildCount());//index);
                pModel.reload(child);
            }
            index++;
        }
    }
}

I've tried creating new nodes before and while expanding the node but the JTree just doesn't seem to update at all. (There is a function outside of this which has JTree validate and repaint.)