AA covers this on their web site:

Except as otherwise explained below, mileage credit is not transferable and may not be combined among AAdvantage members, their estates, successors and assigns. Accrued mileage credit and award tickets do not constitute property of the member. Neither accrued mileage, nor award tickets are transferable by the member (i) upon death, (ii) as part of a domestic relations matter, or (iii) otherwise by operation of law. However, American Airlines, in its sole discretion, may credit accrued mileage to persons specifically identified in court approved divorce decrees and wills upon receipt of documentation satisfactory to American Airlines and upon payment of any applicable fees. Mileage credit is transferable between AAdvantage accounts when offered by AA online, with the shareAAmilesSM program. The member must adhere to the rules and limitations of the shareAAmiles program.
http://www.aa.com/content/AAdvantage...nditions.jhtml