Hi Brahma,
Let me a bit more clear here -
In configuration for a particular output type you can attach a single form. As per your requirement, do as sugg. by Florian i.e. have 2 or 3 different pages. First be Cover letter which i assume would be having static/non flowing data. Second page should have PO details data. Third page would be needed if the PO details layout in case of next page is different from page 2 else page 3 is not needed.
BR.