I've used the CSL Editor, but if I sort first by author and then by issued, the program sorts alphabetically considering all the authors and then the year
Dear Monia, you raised very good question of "sorting bibs w.r.t 1st Author". You may have a look at https://community.endnote.com/t5/EndNote-How-To/How-to-sort-references-by-the-first-name-of-authors/td-p/127346