How to allow any 2 recipients to sign?

Hi,

We are investigating using AdobeSign for integration to our platform. Some of our most common documents allow for any 2 of 4 recipients to sign and complete the document.

For example, Jane, Mary, Mike and John are members, and any two of those can sign and execute the document.

Is there a model of setting this up with AdobeSign? I've tried in the web app (we will eventually be using the API), but all existing models seem to be an all-or-nothing setup.

I thought Recipient Groups would solve this (define groups with all recipients in each), but there is no validation that Mike doesn't sign both portions (he would need to be in both groups).

Any ideas?

Cheers,

Daniel B.