Adding PreferredName to Central User Account???

I have the following script to create the central user account with FirstInitial and Last Name. If firstNAme and LastName already exist add middle initial to the central user account. Please advise:

Now, I would like to add the PreferredName if it exists. Here is the logic:

Create Central User Account with FirstInitial and LastName BUT, If the PreferredName exists create the Central User Account with the first initial of the PrefrredName and LastName.

Here is my current script:

#If Not SCRIPTDEBUGGER Then
Imports System.Collections.Generic
Imports System.Data
#End If

        Public Function AFO_BuildCentralAccountGlobalUnique(ByVal uid_person As String, ByVal Lastname As String, ByVal Firstname As String, ByVal MiddleName As String) As String
           
            Dim account As String
            Dim accountPrefix As String
            Dim f As ISqlFormatter = Connection.SqlFormatter

            AFO_BuildCentralAccountGlobalUnique = String.Empty

            If Firstname.Length > 0 And Lastname.Length > 0 Then
                account = Firstname.Substring(0, 1) & Lastname
            ElseIf Firstname.Length > 0 Then
                account = Firstname.Substring(0, 1)
            Else
                account = Lastname
            End If

            account = VI_AE_FormatConvertUmlaut_Sonderzeichen(account)

            ' we cut it after 12 characters
            account = Left(account, 12)

            accountPrefix = account

            'fill existing addresses in a dictionary
            Dim existing As New Dictionary(Of String, Object)(StringComparer.OrdinalIgnoreCase)
            Dim dummy As New Object()
            Dim dummyPerson As ISingleDbObject
            dummyPerson = Connection.CreateSingle("Person")
            Dim pattern As String = accountPrefix & "%"
            Dim myObjectKey As New DbObjectKey("Person", uid_person)

            Using rd As IDataReader = CType(dummyPerson.Custom.CallMethod("SearchCentralAccount", pattern), IDataReader)

                While rd.Read()
                    Dim accountName As String
                    Dim objectKeyString As String
                    Dim objectKey As DbObjectKey

                    accountName = rd.GetString(rd.GetOrdinal("AccountName"))
                    objectKeyString = rd.GetString(rd.GetOrdinal("ObjectKeyPerson"))

                    If Not String.IsNullOrEmpty(objectKeyString) Then
                        objectKey = New DbObjectKey(objectKeyString)

                        'only addresses which not belong to the actual employee will be considered
                        If myObjectKey.Equals(objectKey) Then
                            Continue While
                        End If
                    End If

                    existing(accountName) = dummy
                End While
            End Using
   Dim UseMiddle As Boolean = False
            While True
                Dim centralAccount As String = account

                ' Does not exists?
                If Not existing.ContainsKey(centralAccount) Then
                    Return centralAccount.ToLowerInvariant()
                End If

                ' next trial
    If Not UseMiddle Then
                 If MiddleName.Length > 0 Then
                  account = Firstname.Substring(0, 1) & MiddleName.Substring(0, 1) & LastName
      UseMiddle = True
     Else
      Throw New ViException("Duplicate Name Alert. No middlename available.")
     End If
    Else
     Throw New ViException("Duplicate Name Alert. Middlename already in use by another Identity.")
    End If
            End While
        End Function