I hope you can find an exact birth date for her. If so, compare it to the day
Easter fell that year. That could account for her being given a third middle name. I have a 2nd great-aunt named
Narcissa Laura C.
Florence. She was the first girl, (born in 1870 like your
Florence), and it seems like her mother was trying to name her after every relative she could. Her siblings only have one or two names. I hope you're able to solve this mystery