The explained scenario is not currently supported by RadSpreadsheet. Genuine data validation is already in our backlog. I encourage you to follow this item
in our Feedback & Ideas portal and upvote it for faster implementation.
Let us know if you have other questions.
Check out Telerik Analytics, the service which allows developers to discover app usage patterns, analyze user data, log exceptions, solve problems and profile application performance at run time. Watch the videos
and start improving your app based on facts, not hunches.