Jstree - Add nodes to tree by user input (button click) - asp.net-mvc

Question

I have a ASP.NET MVC 4.0 project using JsTree. The JsTree is being populated thought a model that returns a JSON.
Now my problem is this, i have a huge tree that makes the user experience pretty bad. What i need is to load a few items (let'say 20), and have a button that when clicked by the user add's the next 20 records to the tree.
I have been searching in Google JsTree documentation and SO, but i haven't found a example that works for me.
Can anyone help me?
Thanks in advanced.
Ok, some break trought. I kind of got this working. In my view the user input call this function:
function getNextRecords() {
var new_data = { "attr": { "ID": "999999999999", "NodeText": "999999999999" },
"data": "999999999999",
"children": [{
"attr": { "ID": "ACT99", "NodeText": "969994222" },
"data": "969994222 - PPP",
"children": [{
"attr": { "ID": "TRFps800", "rel": "disabled" },
"data": "Voz com unlimited 800 fidelização até 01/11/2019",
"state": "open"
}],
"state": "open"
}], "state": "open"
};
var retDom = $.jstree._reference("#demoTree")._parse_json(new_data, -1, true);
$("#demoTree").jstree("move_node", retDom, -1, "inside", false, false, true);
}
This is working fine, expect that the parse json creates a "ul" instead of a "li" any ideas in how to change that?

Answer 1

OK, i finally got this working, this is the final version of my Function i hope this helps someone.
function getNextRecords() {
var new_data = { "attr": { "ID": "999999999999", "NodeText": "999999999999" },
"data": "999999999999",
"children": [{
"attr": { "ID": "ACT99", "NodeText": "969994222" },
"data": "969994222 - PPP",
"children": [{
"attr": { "ID": "TRFps800", "rel": "disabled" },
"data": "Voz com unlimited 800 fidelização até 01/11/2019",
"state": "open"
}], "state": "open"
}], "state": "open"
};
var ref = $("li ul:first")
var retDom = $.jstree._reference("#demoTree")._parse_json(new_data, ref, true);
$("#demoTree").jstree("move_node", retDom, ref, "first", false, false, true);
}
This add a new child after the first UL.

Answer 2

The second part "load part of the branch and with another load of the same branch
load more" is exactly what i'm trying to do but i have not yet succeeded, is it
possible to have an example?
Such task must be taken care of on server side. Take is this way: jsTree only displays whatever is passed to it. So you make a decision what to load in a first go and you can have a button (to reload the whole tree or a branch only) to load more or replace whatever was loaded. Don't forget the logic has (almost) nothing to do with jsTree.