Digital Signatures using Adobe Sign

I have been running into a bit of an issue in utilizing Adobe Sign for digital signatures in Supplier Contracts. Adobe Sign appears to work great when utilizing the Adobe Sign text tags for system generated documents, but when it comes to documents that have been authored outside of the system, things do not seem to work as smoothly. When attorney draft contracts, they will add their own signature blocks which are ignored when routed for signatures and Adobe Sign places new signature blocks at the bottom of the page.

According to PeopleBooks, there should be the ability to type Signature followed by underscores (Signature:____________) and that Adobe Sign will recognize that as a signature field. This does not appear to be the case.