Upvote:3
According to this document from AA:
(...) when all the tickets are in the same PNR. Through check-in will be honored between the following carriers only:
- American Airlines and American Eagle
- oneworld airlines and affiliates
Philippine Airlines is not part of oneworld, so they will not do check-in to the final destination in this situation, even if the tickets were on the same PNR.
(Note that this is in the case of multiple tickets โ they would perform through check-in to a non-OW airline if all flights were on the same ticket).
More details here