Not sure about AA, but a similar attempt on AS was not successful. With AS building a focus city here in SAN, offering nonstop service to many of my preferred destinations, I am making an effort to earn MVP status, missed in 2016 when Hurricane Matthew interrupted travel plans.

When booking a recent flight, I used my LT AA PLT status to book an exit row seat, system moved me to another row when switching to AS MP afterwards. Called AS customer service, agent claims that it is one or the other, expect other carriers to follow a similar practice.