There is another thread somewhere about Flo's tenure in the Marvelettes. I dug up an old Florence Ballard Fan Club Newsletter dated August 1992, and thought this might be of intetest:

Fan Club member David Tague of Westminster, California, conducted an interview with Gladys Horton, lead singer of the Marvelettes, in July, 1991.

David Tague: why was Florence Ballard selected to be a part-time Marvelette over anyone else? Was it a group decision or Berry Gordy's idea?

Gladys Horton: Florence Ballard became a part of the Marvelettes when Wanda Young left to have her first child. It was the group's decision to pick Florence because for some reason Florence was the one that we felt friendlier toward.....not that Mary and Diane were hard to get along with.....Florence was a more warm-hearted person and I don't know, we just felt more close to Florence, and then she also sung high like Wanda did where she would be able to lead the songs that Wanda led in the group. So that is why we picked Florence.

DT: did Florence sing on any recordings made by The Marvelettes?

GH: she didn't sing on any recordings by The Marvelettes but onstage she led "So Long Baby" and "I Want a Guy" but she took Wanda's spot and by her being Katherine's height she made a perfect Marvelette I must say.