Well, once again withot seeing the code I can’t give some exact advices, but if you already have those ids, then you just utilize hidden_field_tag (http://api.rubyonrails.org/classes/ActionView/Helpers/FormTagHelper.html#method-i-hidden_field_tag) to save those values, and then in controller just access params hash and look for the key with the proper name.
hidden_field_tag 'buyer_id', id
I can’t really say more here. You can contact me via e-mail and send some code pieces so that we can discuss more