Spree modify checkout process

Question

I want to customize Spree checkout workflow so way:

1. I want to swap Address step and Delivery step.
2. I want to fill in some fields in Address step automatically and hide them from user.

Example: I have two shipping methods. User should choose one of them. Then I want to show him an Address page. And He should enter only one field - other fields such country, state,city,phone,zip,address I want to insert automatically.

Now I use so way:

Spree::Order.state_machine.after_transition :to => :address do |order|
  address = createDefaultAddress
  order.ship_address = address
  order.billing_address = address
  order.save
end

createDefaultAddress - that's my function, that creates Spree::Address with default data.

And my problem - when I add syntax to change checkout_flow, event after_transition doesn't work. I use

Order.class_eval do
  checkout_flow do
    go_to_state :delivery
    go_to_state :address
    go_to_state :payment, :if => lambda { payment_required? }
    go_to_state :confirm, :if => lambda { confirmation_required? }
    go_to_state :complete
    remove_transition :from => :delivery, :to => :confirm
  end
end

I swap delivery and address, but now my event 'after_transition to address' stop working.

How should I fix it?