Almost Found?

     In my previous post I had written about the discovery of a missing child.

     My 2nd great-grandmother, Teresa already had three children when her daughter, Theresa was born in August of 1902.  In 1908, Albert was born making him the fifth child for Teresa and her husband Stephen.  The 1910 census states that five children were born but only four were living.
     I ended the previous post wondering about that missing child.  When was the child born?  When did he or she die?  Because this child was missing before 1910 and I was looking at the records on Ancestry.com, I completely forgot about the 1905 NY state census.  I have not seen the 1905 census on Ancestry.com yet they have the 1915 and 1925 censuses.  After I posted The Missing Child to my blog is when I thought of looking at FamilySearch.org.
     The 1905 NY state census shows Stephen Duper (head), Teresa Duper (wife), Josephine Duper (daughter), Steven (son), Theresa (daughter) and that's it.  Where was Theresa's older sibling?  The 1902 birth certificate for Theresa Duper states 3 children born prior and four now living but the 1905 NY state census shows only 3 children including Theresa.  So it seems Theresa's older sibling died between August of 1902 when Theresa was born and June of 1905 when the state census was taken.  Maybe the child was living with another relative?  I don't think so.  I have never come across another child's name for my 2nd great-grandmother and my mother doesn't know of any other children. If it weren't for Theresa's birth certificate and the 1910 census I would never know this child existed.  Who was this child and when did he or she disappear?
     I already have my great-grandmother, Josephine's birth certificate but it is the short form and doesn't have the information that her younger sister's certificate has.  I just ordered the long form of Josie's birth certificate to see if it shows any previous children listed for her mother.  Josephine Duper was born in 1894 and her mother was 15 when she married according to the 1930 census.  Did Josie have an older brother or sister who was born between her mother's marriage in 1890 and her birth in 1894?  If Josie's birth certificate is not helpful then I will order the certificate for her brother Steven who was born in 1897.
     I wonder if I could try to order the Child's death certificate now that I've narrowed down the years of death.  I don't have a first name.  All I have is the last name, along with the parents names and the city which was Manhattan.  The address on Theresa's birth certificate in 1902 is the same address as the 1905 NY census.
     Little child, who were you?