Just to make a public note: For a bit of consistency, I've reported (2017 July 10) that "Y'all's" should be accepted. Maybe it's too regional a term, but I've understood it to be the proper possessive of y'all (which is generally accepted for the second person plural "ninyi").
nehrmann84, I think You should Approach The Oxford Printing Press and Advise them to include "Y'all"(s) INTO the Oxford ENGLISH Dictionary. ..... And BTW also take my suggestion for the Past Tense of "Read" to be Changed to "Rede" instead of "Read" which confuses with its Present tense since they are the same> Thank you very much sir!!!!!!
See, what's wrong with that is that "y'all" is used all over America, the largest speaker of English as a first language in the world. It only makes sense that it would be accepted by Duolingo. "Rede" is simply incorrect, and a modification of an existing word, while "y'all" is a widely used constructed word that was not previously part of the English language, at least in recent history. In fact, for this reason, I completely support your suggestion yo approach the Oxford dictionary and encourage them to include a word used by tens of millions. I sincerely hope that cleared up your obvious confusion.