Scroll down this link about 3/4 way down to the heading Separate Tickets.

https://saleslink.aa.com/en-US/resou...ons-irops.html.


This is what is states:

Separate Tickets
 
oneworld re-accommodation

When a customer is holding separate ticket(s) on AA to/from a oneworld carrier in the same or separate PNR, they should be treated as through ticketed customers. 

In the event of a disruption on the originating ticket, the carrier responsible for the disruption is required to reroute the customer to their final destination. 
Travel Agents will need to contact AA Reservations for protection and reissue assistance.
 
AA Reservations 1-800-433-7300 (U.S. and Canada)
Outside the U.S. and Canada, reference Worldwide Reservations Numbers

If the IROPS occurred in a flight on the AA ticket and a refund request is placed, the AA 001 ticket must be refunded through AA and the oneworld through the stock owner's refund department.