Nested form

Hello,

I've got a problem with the creation of a nested form for this
situation

I've got 3 models as follow

Game
-> has_many :authorships

Authorship
-> belong_to :author
-> belong_to :game

Author

belong_to :authorship

In my form the user can enter the author name when creating a new
game.
The application automatically create them if they don't exist but all
is hand made. i'musing a find_or_create under the wood
i would like to use the nested from feature from rails 2.3 for this
form but I cannot figure how to use it to create a new author if it
doesn't exist or find the corect author if it exist.

I somebody got some ideas for helping me, I appreciate much.

Thanks