Hi @janice.b

You can edit registry to prevent add ins to be loaded.

- Disable an Add In as example

- Enable an Add In as example

From the concept above, you can write a script to edit any Add Ins LoadBehavior value to 0 to disable it.

Here is example to make a command line.

So in your batch file, you should have:

- Disable all the add ins you do not want

- Launch Thomson Reuters Eikon - Microsoft Excel by using this command

"C:\Program Files (x86)\Thomson Reuters\Eikon\Eikon.exe" -officeexcel

I'm afraid I'm not entirely sure what you're trying to do here, as specifying a DLL in the list of files to be opened by Excel makes no sense to me. Additionally EikonDesktopDataAPI.dll file has no relation to Eikon Excel COM add-in.
As far as I know /safe command line switch for Excel.exe ensures Excel starts in safe mode, which means all COM add-ins are disabled. In other words no COM add-in can be loaded into Excel running in safe mode, although the behavior may differ depending on the version of Excel. It appears that in latest versions you may be able to use /a command line switch to specify an add-in to load by ProgID. I have not tried this myself, but this is the command line you can try to use if you have Office 2013 or higher:

excel.exe /s /a PowerlinkCOMAddIn.COMAddIn

To the best of my knowledge in earlier versions of Excel /a command line switch is not available. Instead of a batch file you could use the following VB Script, which starts a new instance of Excel and unloads all COM add-ins except Eikon Excel.

Dim m_Excel
Dim i
Set m_Excel = CreateObject("Excel.Application")
m_Excel.Visible = True
For Each m_COMAddin In m_Excel.COMAddIns
    If m_COMAddin.progID = "PowerlinkCOMAddIn.COMAddIn" Then
        m_COMAddin.Connect = True
    Else
        m_COMAddin.Connect = False
    End If
Next
Wscript.Quit