I suppose you have in mind E-form builder of this type:
If so, consider using a combination of our ASP.NET AJAX controls along with asp validators for this purpose. Browse the online demos of the products to familiarize with them and see the variety of scenarios they can be plugged in:
the Telerik team
Watch a video
on how to optimize your support resource searches and check out more tips
on the blogs.
Follow the status of features or bugs in PITS
and vote for them to affect their priority.