There are a handful of programs-- I can think of Etihad and Korean Air, maybe Qatar Airways-- which allow miles to be pooled into a family account or the "head of family"'s account. JAL's program lets family members pool miles for redemption for a fee. Miles can be transferred from member to member in some U.S. programs, but the fee is predictably dear.

The computers will otherwise check the name on the account against the name on the ticket and prevent credits to any mismatched FF number.