I'm trying to do this exact same thing, and yes, it is possible.
I have two versions of the code, one that gives you an input box and allows you to type the template name and retrieves them applies to a reply. And another one that is supposed to the same thing, but use a userform so that the user can choose any templates and apply them with only one click in a nice menu. Unfortunately the second code is broken ( problems with buttons and userform interacting with the module), but the text input one works ok!
Sub AUTOS1()
Dim objItem As Object
Dim mail As MailItem
Dim replyall As MailItem
Dim templateItem As MailItem
Dim templatePath As String
Dim templates As New Scripting.Dictionary
Dim templateName As String
'Add the names and full paths of the templates you want to use here
templates.Add "Shipping", ("C:\Users\user02\AppData\Roaming\Microsoft\Templates\Shipping.oft")
templates.Add "Preadvice", ("C:\Users\example\AppData\Roaming\Microsoft\Templates\PreAdvice.oft")
templates.Add "Documents", ("C:\Users\user02\AppData\Roaming\Microsoft\Templates\Documents.oft")
'Displays a dialog box asking the user to enter the name of the template
templateName = InputBox("Enter the name of the template you want to use:")
'Retrieves the full path of the template from the name entered by the user
If templates.Exists(templateName) Then
templatePath = templates(templateName)
Else
MsgBox "Template not found."
Exit Sub
End If
'Opens the selected template
Set templateItem = Application.CreateItemFromTemplate(templatePath)
For Each objItem In ActiveExplorer.Selection
If objItem.Class = olMail Then
Set mail = objItem
Set replyall = mail.replyall
'Adds the contents of the template to the body of the reply message
replyall.HTMLBody = templateItem.HTMLBody & replyall.HTMLBody
replyall.Display
End If
Next
End Sub
Remember to allow macro and make sure the references for outlook,scripting services,etc are enabled