Yes, I understood BA had no obligation to assist, but it does not hurt to try all options. In any case the point is that although current AA policy is to protect on separate tickets to/from One World carriers many agents are unaware of it and won’t employ the policy, and those that are, are frequently reluctant to call the One World Liasion desk which is what is needed to resolve the issue. Therefore it will not necessarily be a straightforward process and it should be regarded as more of a Hail Mary than a reliable tool.