Our discussions prompted me to look for Cora and Ella in the 1930 census, since they're not with their mom Amelia in the 1930 census. I thought they would be in Maine, but I believe I found both of them in Mass.
I know you found Amelia and her Ogden family in the 1930 census living in Cambridge, MA. In her household are living Thomas & Gladys O'toole, my grandparents, and Dorothy, my aunt.
The very next line down is Ella Ogden's family. It shows Percy Hyson as head of household, Ella as the spouse, and their three daughters Ruth, Lillian, and Florence. I never noticed this before.
I believe Cora Ogden's family is living in Reading, MA in the 1930 census. It shows Carlton Luce, 29 has head of household, Cora as spouse age 26, and their son Carlton B Luce age 6.
The birth locations for both Ella and Cora appear in these two families appear to match their migration from Canada. It looks like both families started off in Mass and must have moved to Maine sometime later.