Originally Posted by
JAXBA
Technically, you'll be on your own, and at the mercy of IB to allow any rebooking.
Basically, nothing. You won't be registered as being through checked - connecting from one partner to another. Global Support only monitor, and support, actual ticketed connections.
Sorry. 
Thank you for comment^
All I can do is just pray for mercy of IB with many flights between MAD-GRX and on-time operation of CX.
I hope MAD allows Sapphire holder to use fast-track immigration.