As the adoption of electronic Signatures increases, a frequently asked question is whether it is a good idea to permit collaboration / editing of a document while its being signed by multiple parties.
In general, when confronted with any such question, it is best to ask what makes sense in the physical world. Electronic Signatures are also signatures and the common sense precautions that apply to physical signatures apply to them as well.
Imagine a situation wherein a document is to be signed by 3 persons - A, B and C. Suppose it has already been signed by a person A. Would it be OK to allow the next signer - person B, to make edits / insertions on the document before he signs it? Indeed, would it be OK to allow B to annotate anything on the document other than his signature? The answer would be clearly "NO". The reason is that any change to the document cannot be made without the concurrence of A, who in this case has already signed the document and therefore isnt a party to the subsequent changes, howsoever minor they may seem. Indeed, A's signature should be invalidated by any subsequent edits made to the document. The same applies to Electronic Signatures as well. Ideally, no edits / insertions / annotations should be permitted in a document once its electronically signed by even one of the signatories. In fact, any good system would expressly prevent such edits / insertions. Any "collaboration" has to happen before the process of signing begins, and should end before the first signature is inserted.
Further, its only common sense that a good Electronic Signing System should not permit the download of partially signed documents. So, signatory B or C should not be able to download a document signed only by signatory A. The document should be made available simultaneously to ALL signatories ONLY after it has been signed by all parties. The document should be invalidated the moment any of the signatories refuses to sign it.