Thanks for all your help folks.
@chaley: your provides strings with various does not work, i still get different series - author folders. I think i have to put more time in this which i do not have for now
BTW, it is not so important to put a Various or first author to the folder name in case of various authors, there could be none, but in case there is only ONE author i would like to have the author after the series name in the folder.
For now i think i stay with a simple series folder

Thanks again