I hate to be vague here, but there may be various answers, and I don't want to deny any of them out of hand.
The situation is this: I have a dynamic form which needs to change hands a few times, with each person along the way digitally signing the form. At some point, the form needs to be locked down to prevent further changes. However, there needs to be a way to unlock the document to allow further changes should the need arise- such as if someone later on notices a typo and it must be corrected, so the document is sent all the way back to the originator, the document must be unlocked, the change made, and then the document re-locked. Preferably, there must be a means to annotate any such changes made.
I had thought I had this originally with digital signatures, but there's no way to unlock a pdf if the signature locks all the fields. So I tried digital signatures which don't lock any fields, which means that the document wasn't locked down. Then I tried encrypting the document with a password to prevent changes, and that was wonderful until I tried to use it on a pdf which had digital signatures, even though those signatures don't lock any fields.
I'm at my wits end, this has been driving me crazy for a few months. I am running Designer ES2- is there anything in it that I can set up to allow this, or barring that, I'll take any advice I can get.