I also have a line that has a George Johnston married to a Placida Cantu Villarreal could this line be related to your grandmother? They had Matias,Josephine,Julia,Willie,Fred, Charlie and Virginia.I have more info on them too! Are they related. This family is from the same area as the Cavazos and they intermarried into the cavazos family. If they are related to you I have more info.