Answer: Though it may be possible in other states, Massachusetts does not allow notarization of a spouse’s signature. Similarly, you cannot notarize for your parent, child, or sibling, including in-laws, step, or half siblings. This rule may be restrictive. But in researching this answer I learned of a much looser standard for notaries.
A notary can notarize for “friends of friends”. What does this mean?
If a signer has no identification, and is not personally known to the notary, there may be hope. Notarization may be allowed if the signer can be identified on the affirmation of a “credible identifying witness”. The word of a credible identifying witness is satisfactory evidence of identity and similar to personal knowledge.
The credible identifying witness must personally know the signer and must be personally known by the notary. An effective chain of witnesses is created. The credible identifying witness should not be involved with the document or have any financial interest in the matter.