angular-dynamic-forms | On-the-fly form generation from data with Angular | Form library

I'm still relatively new to Angular and the logic of this nested JSON is getting the better of me, so I apologize.

I am looking to create a dynamic form and used this tutorial as a starting point.

I am trying to build out conditional fields that will only display if the user selects a certain option. I would like it to work so that if any of my options has children defined in an array, a subsequent input with those children as options appears. I still have a ton of things to consider, but right now I'm trying to get it so that when a user selects Option 2, Option 2A and Option 2B automatically appear in another dropdown underneath.

How can I create an ngIf* statement that says "if the currently selected option has children, add them to another input"?

Here is my code in a sandbox

I have tried checking that the array length of "children" is longer than zero, and also created a boolean called "hasChildren" and manually assigning a true/false value to check against (though I don't prefer this solution because the finished app will have many nested options and it would be easier to just check if the array is empty or not).

I also tried this solution but must have had a syntax error, because it didn't work for me.

HTML: