The DM household option is a valid feature for RE7.  However, RE7 does not have “household” records like CRM does.  RE7 only supports a concept of “head of household”.  For example, in RE7, if you have a couple living together and are listed as spouses, you may mark one  as the “head of household.".  In DM, we essentially treat the RE7 “head of household” as if it was a CRM “household” record.