WordPress Import

Hello

I have several websites

I have 95% of custom posts in my website, I have a lot of posts in common

I use Import/ Export of wordpress. Its a good solution (with the further help of a plugin to modify the links in the database)

BUT the only concern is that the import tool does not have the possibility to update the posts, just to create them…

do you know the possibility of modifying this tool to allow the update ??

I tested several plugins without success whether import / export or sync