Factory Girl: can one reopen factory definitions and complete them?

Hi have this special use case, in which I have to define a factory in one file without a certain parameter, and then insert it in the factory definition later. This is a case where I am importing factory definitions from an external dependency (gem, plugin, whtv) and I need to extend it in my project. Something like:

# external def
FactoryGirl.define do
  factory :user do
    email "somebody@somebodysworld.com"
  end
end


# proj def
FactoryGirl.define do
  factory :user do
    password "qwerty"
  end
end

this code doesn't work, cuz factory girl thinks I'm redefining the factory. But what I'd really want would be extending it. Is this possible?