Need Suggestion on handling multiple associated models

hi guys…

I am new to rails and need some pointers on how i should handle multiple related models.
’ ’ => model
In my app i am creating and handling some ‘deals’. Each ‘deal’ has got some ‘orders’, and each ‘order’ has certain ‘duties’.
Now what i am doing currently is, on the new_deal page itself, i am dynamically adding orders for that deal (using attribute_fu).

I also need some ajax functionality on this page. but that works for only the fields that are initialy present on the page, when its loaded (as i am not able to set the id’s for dynamic fields)

Can you guys suggest me some other better way to handle the above scenario. i have asked at many forums, channels and they always tell me to avoid using mutiple models in a single page.