Hi Kevin,
in order to achieve what you want the simplest way is to trigger Ultradox right from the form.
I've added a building block (Load form data) so that you can trigger Ultradox on Form submissions.
I've switched on the trigger in the Form add-on.
You will then get a structured list of documents. I've then filtered the list to only keep checked values (Filter list block).
Then you can simply use the list-generation feature in Ultradox templates to create a list with the checked values.
Let me know if this works for you.
Best,
Daniel