In my earlier experience, I always got non-shared codes when getting rebooked for involuntary reroute. It was nice getting rerouted in from LH onto AY Y, or from AA O to AY I

But last time, I went from AA-coded LAX-LHR-HEL (on BA-AY), to LAX-JFK-HEL (obviously on AA-AY) also AA-coded AY Y would have earned 15,000 points instead of ~6600

Is this how AA does it??