How to 'CreateFormXObjectFromPDFPage' without making resource copy when modify PDF ?

[ArcRain]

I want to make a page thumbnail and place it in a rectangle at last page in same pdf file.
So I use 'ModifyPDF', 'CreatePDFCopyingContextForModifiedFile', 'CreateFormXObjectFromPDFPage' to solve it.
But I found the file size is almost double size than original.
I think it maybe the page resource copy make it. Because the page include some image object.
Then it's copied when I using 'CreateFormXObjectFromPDFPage'.
How can I resolve it? Is it possible to reference it without copying?

P.S: Thanks for your great project!