I can't be sure that either Emma in the 1880 census was yours, but they were the only ones in TN that were near her age and with a birth state of TN as given in the 1900 census. And your Margaret may have either been the Mattie OR the Maggie in the 1900 census - the names are similar. I cannot locate John without knowing his father's name if his age was similar to Mattie or Maggie's - he would still be living in his father's household in the 1900 census. I have a national 1880 census index and transcripts but the rest of my CD's are for Davidson Co. TN. I do have access to a national 1900 index but it is cumbersome and full of errors - and it only lists head of households (not every individual in the household) and you almost have to know the state and county where the individual can be found because there were so many individuals in the nation by 1900.