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.

You cannot transfer miles between BA and AA (at least not unless you lose a significant portion of it).

Stick with AA. They should earn miles on the BA flight in the AAdvantage programme. (although I don't know it well enough to know whether they exclude any particular fare classes). Presumably there are also more non-flying mile earning options in AA for those based in the US...

Since they are unlikely to reach status, or get so many miles as to redeem for travel in Business Class, you'd want to avoid BA Executive Club, where economy redemptions on BA are usually horrible value given the fuel surcharges, taxes, etc. added.

I would suggest Advantage. The points earning will be the same, but redemption rates are typically lower plus AA does not charge fuel surcharges ( other than for redemptions on BA/IB ) so no large cash componant to pay on awards

Thanks Guys, I will register them for AAdvantage in in that case. I hope it does not matter that the first miles after registration are on a partner and not AA Flown right?

It does not matter