What term describes a signer who is substituting for the original signer?

The term that describes a signer who is substituting for the original signer is "substitute signer." This refers to a situation where an individual steps in to sign a document on behalf of another person who is unable or unwilling to do so. The role of the substitute signer is to ensure that the signing process can continue, despite the absence of the primary signer. This is particularly relevant in documents requiring notarization, where the notary must confirm the identity of the substitute signer as well as their authority to act on behalf of the original signer.

The other options do not accurately capture this scenario. A primary signer refers to the individual who is originally responsible for signing the document, while a witness signer may be present to observe the signing process and confirm the identities of the parties involved, but they do not substitute for the signer. An acknowledging signer is someone who acknowledges their signature in front of a notary, but they are not acting on behalf of someone else. Understanding these distinctions is key for notaries when handling various signing scenarios and ensuring proper compliance with legal requirements.