Travel funds are only useable by the passengers name who is on them the funds are not transferable.
Soon southwest will have a new way for you to transfer travel funds in to rapid rewards points which your family member can do once the feature is available then those points can be used to buy a flight for anyone. That family member would need to have a rapid rewards account for the points to go in to and currently there is no official date on when this option will be available.
-Blake
