Here's a quick overview of the family involved: Mary Ann Keegan had a child, Mary E. Showler, by her first husband. Mary Ann later married John Mullett. Mary E. Showler married John Francis Downey. After John Downey's death, Mary E. married George Tootill.
Looking more closely at the record, other pieces fell into place (besides approximate ages). Mabel F. Merry was born in Massachusetts, like Mabel F. Downey. George Tootill's listed relationship to the head of household, Carlton R. Merry, was father-in-law. If Mabel F. Downey was in fact one of Mary E. Showler and John Francis Downey's children, George Tootill would have been her step-father and probably recorded in a census as the father-in-law of her husband if they were living together.
Furthermore, Mabel F. Merry's father was listed in 1910 as born in Maine, and her mother was listed as born in England. As discussed in my previous post, John Francis Downey was born in New Brunswick, Canada, and Mary E. Showler was usually recorded with the birthplace England. So the mother's birthplace matched. Although Mabel Merry's father's place of birth was listed as Maine and not New Brunswick, a few things kept my hopes up that this was the mystery Mabel from 1900. Census records are notoriously unreliable because only one person in the household provides all of the detail for everyone else. So, there are often errors. I normally wouldn't try to force a connection with such a glaring difference in locations, but
Armed with this new find and feeling like this connection was more than a hunch, I added Mabel F. Downey to my family tree as the daughter of Mary E. Showler and John Francis Downey, with Carlton R. Merry as her husband, noting that this was all still theory. I still couldn't find any record of her birth or marriage on Ancestry or FamilySearch. However, Ancestry started shaking a little green leaf at me, and for once, the hint it had for me cracked the case. When I clicked the hint, I got a "California Death Index, 1940-1997" record for Mabel F. Merry. California?! Not likely. I read the record anyway. This Mabel's birthday was January 31, 1878, and her birthplace was Massachusetts. Actually, this looked like my mystery Mabel so far. This woman died on June 4, 1965 in Los Angeles. Unlikely for my family, but there was one more line to the index record: "Mother's Maiden Name: Schoular." Say "Showler" out loud; now say "Schoular" (with a little bit of a German twist on the "ou" part-- the marriage record indicates Mary E. was born in Bremen, Germany, not England). BINGO!! Not only was this my Mabel F. Downey, but I have my first piece of unambiguous evidence that she was in fact the previously unheard-of daughter of Mary E. Showler and John Francis Downey.
I can't answer why Mabel Frances Downey's siblings have Massachusetts birth records on FamilySearch while she doesn't. I can't answer why she previously was unknown to my family (although later finding that she was already in Los Angeles in the 1930 U.S. Census as "Frances M. Merry" indicates she wasn't close to the rest of the family who stayed in southern Connecticut). What I do know, however, is that her son's Massachusetts birth record says she was born in Worcester, Massachusetts, where one of her other siblings was born. I also know that one of her sisters, Margaret Ann Downey, used the surname Downing in her own marriage record, which would explain finding "Mabel F. Downing" in the 1900 Springfield City Directory. Lastly, there are just way too many connections for this to be a mistake. After more than a year of wondering who this mystery Mabel was, I finally uncovered a new sibling, brother-in-law, niece, and nephew to my great-grandfather. An entire branch of the family had moved away and been forgotten, and I found them.