We have added the Main user based on the logins of the last 30 days.
Select Top 1000000 tblAssets.AssetID,
  tblAssets.AssetUnique,
  tblAssetCustom.Manufacturer,
  tblAssetCustom.Model,
  TsysChassisTypes.ChassisName,
  tblAssetCustom.Serialnumber,
  tblNetwork.MACaddress,
  tsysOS.OSname As OS,
  tsysOS.Image As icon,
  tblAssets.Processor As CPU,
  tblComputersystem.NumberOfLogicalProcessors As Cores,
  Replace(Replace(tblAssetCustom.PurchaseDate, '00:00:00', ''), '12:00AM',
  '') As [Purchase Date],
  Replace(Replace(tblAssetCustom.Warrantydate, '00:00:00', ''), '12:00AM',
  '') As [Warrenty EXP Date],
  tblADComputers.OU As Dept,
  tblState.Statename,
  tblAssets.Lastseen,  
SubQuery3.Domain,
  SubQuery3.Username,
  SubQuery3.LoginsFrom tblAssets
  Inner Join tblNetwork On tblAssets.AssetID = tblNetwork.AssetID
  Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
  Inner Join tsysOS On tblAssets.OScode = tsysOS.OScode
  Inner Join tblSystemEnclosure
    On tblAssets.AssetID = tblSystemEnclosure.AssetID
  Inner Join TsysChassisTypes On TsysChassisTypes.Chassistype =
    tblSystemEnclosure.ChassisTypes
  Inner Join tblADComputers On tblAssets.AssetID = tblADComputers.AssetID
  Inner Join tblComputersystem On tblAssets.AssetID = tblComputersystem.AssetID
  Inner Join tblState On tblState.State = tblAssetCustom.State 
 Inner Join (Select Top 1000000 tblAssets.AssetID,
    Max(SubQuery1.Logins) As MaxLogins
  From tblAssets
    Inner Join (Select Top 1000000 tblAssets.AssetID,
      tblCPlogoninfo.Domain,
      tblCPlogoninfo.Username,
      Count(tblCPlogoninfo.ID) As Logins
    From tblAssets
      Inner Join tblCPlogoninfo On tblAssets.AssetID = tblCPlogoninfo.AssetID
    Where tblCPlogoninfo.logontime > GetDate() - 30
    Group By tblAssets.AssetID,
      tblCPlogoninfo.Domain,
      tblCPlogoninfo.Username) SubQuery1 On SubQuery1.AssetID =
      tblAssets.AssetID
  Group By tblAssets.AssetID) SubQuery2 On SubQuery2.AssetID = tblAssets.AssetID
  Inner Join (Select Top 1000000 tblAssets.AssetID,
    tblCPlogoninfo.Domain,
    tblCPlogoninfo.Username,
    Count(tblCPlogoninfo.ID) As Logins
  From tblAssets
    Inner Join tblCPlogoninfo On tblAssets.AssetID = tblCPlogoninfo.AssetID
  Where tblCPlogoninfo.logontime > GetDate() - 30
  Group By tblAssets.AssetID,
    tblCPlogoninfo.Domain,
    tblCPlogoninfo.Username) SubQuery3 On SubQuery3.AssetID = SubQuery2.AssetID
    And SubQuery3.Logins = SubQuery2.MaxLoginsWhere tblAssetCustom.Model <> 'Virtual Machine' And tblNetwork.IPEnabled = 1 And
  tblComputersystem.Domainrole = 1
Order By tblAssets.AssetName