Outlook contacts is based on the traditional system, allowing two people to
be listed in a household who share the same last name:

Charlie & Pamela Schmidt
123 Harrowsgate Drive
Citytown, NY 14004

Contacts does not, however, allow for two people living in the same
household with different last names (e.g., cohabitation):

Ben Cole, Jr. & Amy King
2600 Mountain Drive
Denver, CO 12345

I am trying to send out holiday cards and don't know what to do.

Thanks.