We had no problem using E-Signature last tax season for returns where a married couple share an email.  Two emails went out to the same email address, one for each spouse.  As long as they answer their authentication questions everything was smooth.

We did run into problems with returns for minors.  They don't have enough credit history to populate any knowledge based authentication questions so every single one of the ones we tried failed authentication.  Have not come up with a solution for this situation.