I was researching my great aunt's family. She was Matilda Koch married to Frank METZ, They were from Germany. I had her parent's and siblings but could not find her and her husband and children until 1910. Today I was reviewing again and I realized the New York State 1892 census had my great aunt's family living at the same residence, just with the surname WALTER. I then saw the 1900 Federal Census showed them again with the surname WALTER. All the names and dates of birth matched them but in 1910 it changes to METZ and those who had SS cards show Metz and they are Metz in wars and headstones. I do not have a reason whey there would be such a drastic change. Is there anyone familiar with this family?