Hi,
You can accomplish this by making use of client side api for RadDatePicker. You need to attach
"OnDateSelected" client event to first RadDatePicker and then enable/disable the other DatePickers by using
set_enabled()
method.
The following links will be helpful in client-side access to RadDatePicker.
Client-Side Basics
RadDatePicker Client Object
Please write again if you need further assistance.
Regards,
Shinu.