I would like to give the user with the option to call a new Form from within a partially completed Form. To then complete the called Form, and return to the original Form to continue processing . Is this possible ? What is the best way to achieve this ?
I don't think this is possible.
You may think of creating multiple pages within a PDF and show/hide based on filling-criteria. But you will loose the design granularity.
Adobe Flex based forms would better do for this case.