Write text to a multi page tiff.

I need something that seems pretty simple.
I user needs to download a multi page tiff and on the first page I need to write some text on it. Like a watermark at the top left, but with text.
I can easily do this on a one page tiff (see below), but when it comes to multi page tif is more complicated. It needs to be all done in memory, I don't want to have to save the first page of the tif to a file and add additional pages to it, then display it, then delete the edit file. 

Dim img As Image Dim inp As New IntPtr Response.AppendHeader("content-disposition", "attachment; filename=" + name) img = New Bitmap(fullpath) img = img.GetThumbnailImage(img.Width, img.Height, Nothing, inp.Zero) Dim objFont As New Font("Verdana", 40, FontStyle.Bold, GraphicsUnit.Pixel) Dim grDrawString ...