New user created and added to the built-in administrators group

Original query, unchanged.

(union isfuzzy=true
    (SecurityEvent
    | where EventID == 4720
    | where AccountType == "User"
    | project CreatedUserTime = TimeGenerated, CreatedUserEventID = EventID, CreatedUserActivity = Activity, Computer = toupper(Computer), 
    CreatedUser = tolower(TargetAccount), CreatedUserAccountName = TargetUserName, CreatedUserDomainName = TargetDomainName, CreatedUserSid = TargetSid, 
    AccountUsedToCreateUser = SubjectAccount, CreatedByAccountName = SubjectUserName, CreatedByDomainName = SubjectDomainName, SidofAccountUsedToCreateUser = SubjectUserSid
    ),
    (WindowsEvent
    | where EventID == 4720
    | extend SubjectUserSid = tostring(EventData.SubjectUserSid)
    | extend AccountType=case(EventData.SubjectUserName endswith "$" or SubjectUserSid in ("S-1-5-18", "S-1-5-19", "S-1-5-20"), "Machine", isempty(SubjectUserSid), "", "User")
    | where AccountType == "User"
    | extend SubjectAccount = strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
    | extend SubjectDomainName = tostring(EventData.SubjectDomainName), SubjectUserName = tostring(EventData.SubjectUserName)
    | extend TargetAccount = strcat(EventData.TargetDomainName,"\\", EventData.TargetUserName)
    | extend TargetUserName = tostring(EventData.TargetUserName), TargetDomainName = tostring(EventData.TargetDomainName) 
    | extend Activity="4720 - A user account was created."
    | extend TargetSid = tostring(EventData.TargetSid)
    | project CreatedUserTime = TimeGenerated, CreatedUserEventID = EventID, CreatedUserActivity = Activity, Computer = toupper(Computer), 
    CreatedUser = tolower(TargetAccount), CreatedUserAccountName = TargetUserName, CreatedUserDomainName = TargetDomainName, CreatedUserSid = TargetSid, 
    AccountUsedToCreateUser = SubjectAccount, CreatedByAccountName = SubjectUserName, CreatedByDomainName = SubjectDomainName, SidofAccountUsedToCreateUser = SubjectUserSid
    )
  )
| join kind=inner
(
  (union isfuzzy=true
    (SecurityEvent 
    | where AccountType == "User"
    // 4732 - A member was added to a security-enabled local group
    | where EventID == 4732
    // TargetSid is the builin Admins group: S-1-5-32-544
    | where TargetSid == "S-1-5-32-544"
    | project GroupAddTime = TimeGenerated, GroupAddEventID = EventID, GroupAddActivity = Activity, Computer = toupper(Computer), GroupName = tolower(TargetAccount), 
    GroupSid = TargetSid, AccountThatAddedUser = SubjectAccount, SIDofAccountThatAddedUser = SubjectUserSid, AddedByAccountName = SubjectUserName, AddedByDomainName = SubjectDomainName,
    CreatedUserSid = MemberSid
    ),
    (  WindowsEvent 
    // 4732 - A member was added to a security-enabled local group
    | where EventID == 4732 and EventData has "S-1-5-32-544"
    //TargetSid is the builin Admins group: S-1-5-32-544
    | extend SubjectUserSid = tostring(EventData.SubjectUserSid)
    | extend AccountType=case(EventData.SubjectUserName endswith "$" or SubjectUserSid in ("S-1-5-18", "S-1-5-19", "S-1-5-20"), "Machine", isempty(SubjectUserSid), "", "User")
    | where AccountType == "User"
    | extend TargetSid = tostring(EventData.TargetSid)
    | where TargetSid == "S-1-5-32-544"
    | extend SubjectAccount = strcat(tostring(EventData.SubjectDomainName),"\\", tostring(EventData.SubjectUserName))
    | extend SubjectDomainName = tostring(EventData.SubjectDomainName), SubjectUserName = tostring(EventData.SubjectUserName)
    | extend TargetAccount = strcat(EventData.TargetDomainName,"\\", EventData.TargetUserName)
    | extend Activity="4732 - A member was added to a security-enabled local group."
    | extend MemberSid = tostring(EventData.MemberSid)
    | project GroupAddTime = TimeGenerated, GroupAddEventID = EventID, GroupAddActivity = Activity, Computer = toupper(Computer), GroupName = tolower(TargetAccount), 
    GroupSid = TargetSid, AccountThatAddedUser = SubjectAccount, SIDofAccountThatAddedUser = SubjectUserSid, AddedByAccountName = SubjectUserName, AddedByDomainName = SubjectDomainName,
    CreatedUserSid = MemberSid
    )
  )
)
on CreatedUserSid
//Create User first, then the add to the group.
| project Computer, CreatedUserTime, CreatedUserEventID, CreatedUserActivity, CreatedUser, CreatedUserSid, CreatedUserAccountName, CreatedUserDomainName,
GroupAddTime, GroupAddEventID, GroupAddActivity, GroupName, GroupSid,
AccountUsedToCreateUser, SidofAccountUsedToCreateUser, CreatedByAccountName, CreatedByDomainName, 
AccountThatAddedUser, SIDofAccountThatAddedUser, AddedByAccountName, AddedByDomainName
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| project-away DomainIndex