Title: Either/Or signing (one-of-many authorized signer)

Request: Add an “either/or signer” recipient type so a document can be sent to two (or more) authorized signers, but only one signature is required to complete the document.

Expected behavior:

Sender selects a signer group (e.g., Signer A OR Signer B).
The document completes when any one signer in the group signs.
Once one signer completes, the remaining signer(s) are automatically marked as not required and can no longer sign.
Audit trail/certificate records who signed and that the others were optional.
Optional: ability to restrict the group to specific emails/domains for compliance.
Why it matters: Many organizations have multiple people with signature authority, and today we have to rely on forwarding or manual cancellation, which is error-prone and harder to control.