Thank you for your suggestion,

Actually, there is a way...I've managed to do something: on the main document I've created a bookmark at the beginning of each certificates, then I've created another document to finish and merge ( with conditions on each level ) I insert the main document as a link within the condition ("Text from file") I specify the "Range" for each condition (Level 1 will have bookmark1 etc..)
I then create a filter on level to have them in order...
I still have some issues with the formatting of the different texts...