There are two fundamental architectures for forms... XFA and PDF, or
what we call Acroforms. XFA forms can only be editted in LiveCycle
Designer. But the good news is that you can edit the fields and the text
and page artifacts in LC Designer.So it's not a matter of how it was
generated, but what it was designed in. Once a form has been done in LC
Designer (XFA/XDP) it can only be edited with LC Designer. Acroforms can
be edited in Acrobat, but your changes are (primarily) limited the form
field...