Cross Site Form Submission

Hi guys,

General Question: How to do Form submission between 2 CI application.

CI1 : http://www.example.com
CI2 : http://sub.example.com

Form is on CI1 & it is submitted to CI2.

Both apps are configured with CSRF & XSS enabled.

Any way to "whitelist" CI1 in CI2 so that it does not generate an error & allow CI2 controller to process CI1 post request.

Thanks!

-- Khalil