Dear Macropod,
I actually used the footer field method exactly as described in >>
this link <<. I think that word interprets the bookmark as a nested INCLUDETEXT instruction and after to much documents, it throws nesting error.
Anyway, I manually sat the initial page number of all my files, in the end it was easier... Combining field-based page numbering and automated table of contents accross several documents doesn't seem an easy task for word...
Best