Hello,
In your situation, the best is to ask the complementary question in the form, to not create a new task AFTER.
1/ First proposition
Thanks to AngularJS, in the UI Designer form, you can detect that you need more answers, then show up the question.
Example, I create a JAVASCRIPT variable named "formControl":
var formControl = { "showAdditionnalQuestion" : false }
if ($data.country == "FRANCE")
formControl.showAdditionnalQuestion = true;
return formControl
then, create a Container, and in the Hidden property, give " ! formControl.showAdditionnalQuestion"
That's it: the additional question is visible only when the country is France
2/ Second proposition
If you have to do some back-office control, then you can implement them via a REST API. Then, you still can ask the additional question in the same task
3/ By the process
If you have to execute some back office in the process, then create a second task in your process.
You can use an Actor Filter to specify which user can realize the task. You can specify that the same user who executes task 1 must execute Task 2
I don't like so much this way because the user valid the task, and then another task comes. if the user has a lot of tasks, he may see the additional task some hour after.
last, if the user goes to vacation, the second task may be executed after multiple days.