flatten Lifecycle Designer form

Hello, I have a form in Acrobat 8 Professional that once all the data has been entered and the last person has signed it the file is flattened to prevent changes to the form. The next user can then insert other pdfs as we gather more information. eventually we have one PDF that contains all the information a user needs.

I wanted to convert this form to a lifecycle designer format but

1) I cannot flatten the file, the Javascript does not work
flattenPages(0)

2) It will not permit me to insert other pdf to this file.

Any help would be great.