Sort table so that linked rows show up as subsets in overall alpha sort
So - making the following assumptions:


memKey is the same for a family head and all subsidiary memberships for the family;
There is no direct pointer to the family head record in a subsidiary member row.
isFamHead acts as a Boolean, where "1" means the row represents a family head, and "0" means it doesn't.
There is only one row for any given memKey where isFamHead = 1


From the comments: Members with "single" memberships (1 person, no family) will have isFam = 0. Members who are part of a family membership will have isFam = 1; only the primary member from the family will have isFamHead = 1, it will be 0 for the rest.

Something like this should work. Column and table names are made up, of course, since none were provided except for the three relevant columns.

SELECT CASE WHEN `isFamHead` = 1 OR `isFam` = 0 THEN CONCAT(lastname,', ',firstname) ELSE '' END
       as FamilyHead
      ,CASE WHEN `isFamHead` = 0 AND `isFam` = 1 THEN '' ELSE CONCAT(lastname,', ',firstname) END
       as FamilyMember
      ,'blah blah' as Additional_Columns
  FROM (
        SELECT fh.lastname as fh_lastname
              ,fh.firstname as fh_firstname
              ,m.*
          FROM member m
                 INNER JOIN member fh ON (m.memKey = fh.memKey AND fh.isFamHead = 1)
       ) sq
 ORDER BY fh_lastname, fh_firstname, memKey, isFamHead DESC, lastname, firstname;


Our subquery adds the first and last name of the isFamHead row for the current row's memKey to the current row's data.

Then, we sort by:
 - the family head's last and first names
 - memKey (just in case there are two family heads with the same name - this pulls each actual family group together)
 - isFamHead in descending order - this makes the family head the first row of each family group
 - finally, the members' last and first names.

If we have the following families:


John Smith (head), Jane Levy, Paul Smith-Levy, Frank Smith (memKey = 10000)
John Smith (head), Patty Smith, Jack Smith, Alvin C Monk (memKey = 10001)
Adrian Monk (head), Trudy Monk, Ambrose Monk
Steve Rogers (a single member)


This should give us the following output:

Family Head          Family Member
------------------   -------------------
Monk, Adrian
                     Monk, Ambrose
                     Monk, Trudy
Rogers, Steve
Smith, John
                     Levy, Jane
                     Smith, Frank
                     Smith-Levy, Paul
Smith, John
                     Monk, Alvin C
                     Smith, Jack
                     Smith, Patty


NOTE: code is untested.