Reinstall ECC with XI

Guys,

I have a doubt about reinstall ECC server.

Originally our ECC server was installed without XI part but now situation changed, some external system is required to integrate with our main ERP system.

Our team finally decided to add XI part to ECC server.

But we don't know whether technically SAP allows us to reinstall ECC with XI(use the same instance name) and current data in system retain untouched.

Is it possible?

Thanks for any suggestion.