Hello,
Pardon me if This has already been asked/answered and is a re-post,
I have a flight coming up on BA on Fare Class V Economy for my parents, Currently they not have a membership in either BA or one of the Oneworld partners, If most of their travel is within Continental U.S and use BA for one international travel every year, would it be advised to Join AA program and have the miles from trip on BA be transferred to AA Account or join BA and use the Points from BA account on partner airlines for flights within US?

One Advantage I see on AA is that the Award Flights seem to be available right out of their closest Airport (EWR). For Some reason BA.com does not return any flights on Avios calculator out of EWR. Also AA seems to have other partners such as Etihad, Jet Airways.

They are also planning a Europe Travel this year. Could the Oneworld/AA/BA Experts please Advice on the best approach to maximize the benefit given that they are not frequent flyers. Highly appreciate your support.