Insert a docx file into another docx file with PHP (and openTBS)

I use the PHP plugin OpenTBS to fill in placeholders in a Word .docx Document with normal ASCII text from a HTML form. Is there any possibility to insert the content of another docx file at a certain position (placeholder) in the template docx file? The important requirement is, that the text in the output file should be still formatted as the text in the input file.

via Chebli Mohamed