The last odd page of a document

[jbeyogo]

Hello,

I'am using XSLT-FO with FOP 0.96 to generate, at one time, a list of PDF's documents. The generated documents will be automatically printed, at one time, in duplex format. So, i have to separate all the documents by making a specific treatment on the last odd page of all document as shown bellow :

For 3 pages :

1st page : no specific treatment
2nd page : no specific treatment
3rd page : specific treatment
4th page : blank because of the duplex printing format.

For 4 page :

1st page : no specific treatment
2nd page : no specific treatment
3rd page : specific treatment
4th page : not-blank and no specific treatment because of the duplex printing format.

For 2 page :
1st page : specific treatment
2nd page : not-blank and no specific treatment because of the duplex

For 1 page :
1st page : specific treatment
2nd page : blank because of the duplex printing format.

I have no problem when the last page of one document is an odd page. But when the last page is an even page I do not see how to make a specific treatment in the page before ?
I need a help, I need a help,........