I am look for advice on how to track down the birth records/biological parents of Harry (b 1882), Albert (b 1887) and Oscar (b. 1890) "Stratton". There mother was Elizabeth Kellum. I have come to the conclusion that Maurice C. Stratton could not be their biological father, because he would was not old enough at the time of their birth.

I original thought that I could request the three brother's birth certificates, until it dawned on me that their Surname was not going to be listed.

Does anyone have any ideas on how to research my question? Do birth certificates of the 1880s typically list the mother's maiden name and are searchable? Would it have been likely that the boys were formally adopted because they have the new surname and there would be a record of that?