Originally Posted by Gaza

You would be much better posting this on the AA forum. As apudme says, you cannot earn or redeem AA or BA miles on either carriers routes from London to the USA. You can redeem AA and BA Miles on each carriers services between the USA and Manchester (MAN).

There is nothing stopping you redeeming AA Miles on direct AA services between the US and Europe. Equally there is nothing to stop you redeeming AA miles on BA flights to Mexico, Canada or the Caribbean and then taking an AA connection.