The problem I am having is that when I append the second file and drag the element on to a new page, the anchored graphics come in at their original sizes.
Why would they not? Have you told them to do otherwise, such as with an Object Style?
I would try that!
We need to have multiple files since the XML will be downloaded from individual product web pages.
With InDesign XML, as with other XML operations, you should anticipate having to transform the XML before you import it into another product. That transformation might very well involve mere concatenation of multiple XML files, or a more complicated merging operation. To be blunt: that is not a compelling reason.
Can you use an Object Style as an XML attribute? The documentation I have read only has Paragraph and Character style attributes for the aid5 namespace. I thought if the frames had their fitting set on the first page that cloning would theoretically keep the fitting options for subsequent pages. This only holds true when all of the XML is in one file and is merged and not when multiple files are appended.
I understand that concatenating the XML will probably be the solution. Appending multiple XML files in ID seemed like an easier approach for the graphic designers to handle.
Can you use an Object Style as an XML attribute?
I'm not aware that you can, though I don't say that you can't.
It's not what I meant, though.
Can you set the Basic Graphics Frame object style to have auto-fit
and then make sure it is the selected default style (i.e. highlighted
in the Object Styles panel when nothing is selected) before you do your
Setting the Object Style to fit and having it as the default did not work.
Does it have anything to do with the graphic frames already on the first page and when inserting a second page the graphic frames are not there? That would not explain why it would work correctly if the XML was contained in one file.