Can we design such a form using Orbeon form builder which can be download as a fillable pdf. Later we could capture data into multiple such downloaded fillable pdf of same form offline, and able to import those filled pdf form into existing set of online submitted form.
If I understand you properly, you would like Orbeon Forms to (1) produce a PDF (2) with fillable fields, and then be able to (3) import this PDFs which was filled by users, potentially offline. Is this correct?
Right now, Orbeon Forms does 1, but not 2 and 3. However, adding those capabilities would be quite inline with the direction of the product, and maybe something we could implement for you as a "sponsored feature" under a Dev Support plan, if this is something that could make sense for you.
Follow Orbeon on Twitter: @orbeon
Follow me on Twitter: @avernet