This feature is similar to the document assembly performed by Pathagoras in its standard Word operations.
To assemble Adobe Acrobat forms, select the Assemble button from the Action column. The screen will expand and more instructions will be presented. Select from the PDFs dropdown list at the left the ones you want to assemble. Pathagoras will place your selection in the 'To be assembled' panel at the right. You can rearrange your choices, and delete any erroneously selected choices. When ready to proceed, click 'Assemble'.