Include more fields in greeting tag

Why would you have all field options available for the Subject Line, and only three for the Greeting? This is unacceptable, as there is a very good reason for custom fields for this greeting purpose. Let me explain: email addresses are singular. However, when we send an email from Constant Contact, we would like to address it to the collective family or household. Why? Because our memberships (and I assume other CC clients) are by Household, not by email address! So, our custom field (Greeting Name) is "Gerry & Mary," or "Harris Family," for example.