Ibooks sorting pb macbook/Ipad

Using Mavericks on macbook pro 2011. Using Ibooks on MacBook Pro and Ipad in order to keep a common library of PDFs. Primary source of downloading PDFs can be either my macbook or my pad. Synchronising is on. I synchronise all books through Itunes. I use collections and everything is sorted on my macbook by "most recent".

When synchronising all books the sorting is not respected on my ipad. Moreover when sorting by "most recent" directly on the Ipad, the sorting is not correct.

Apple store could not help me and proposed to look for another more specialized app for PDFs.

Could not find any app working fine when not connected to the internet and actually I would like to use Ibooks and fix this frustrating problem. Please ipad do use the same sorting as my macbook.

Any tips?