wivesofjosephsmith.org
suggests this for Fanny Alger
http://www.wivesofjosephsmith.org/02-FannyAlger.htm
At the time, Fanny was living in the Smith home, perhaps helping Emma with house work and the children. Ann Eliza Webb recalls, “Mrs. Smith had an adopted daughter, a very pretty, pleasing young girl, about seventeen years old. She was extremely fond of her; no mother could be more devoted, and their affection for each other was a constant object of remark, so absorbing and genuine did it seem”.
and this:
Chauncey Webb recounts Emma’s later discovery of the relationship: “Emma was furious, and drove the girl, who was unable to conceal the consequences of her celestial relation with the prophet, out of her house”. Ann Eliza again recalls: “...it was felt that [Emma] certainly must have had some very good reason for her action. By degrees it became whispered about that Joseph’s love for his adopted daughter was by no means a paternal affection, and his wife, discovering the fact, at once took measures to place the girl beyond his reach...Since Emma refused decidedly to allow her to remain in her house...my mother offered to take her until she could be sent to her relatives...”
and this:
Book of Mormon witness, Oliver Cowdery, felt the relationship was something other than a marriage. He referred to it as “A dirty, nasty, filthy affair...” To calm rumors regarding Fanny’s relationship with Joseph, the church quickly adopted a “Chapter of Rules for Marriage among the Saints”, which declared, “Inasmuch as this church of Christ has been reproached with...polygamy; we declare that we believe, that one man should have one wife...” This “Article on Marriage” was canonized and published in the Doctrine & Covenants. In 1852, the doctrine of polygamy was publicly announced, thus ending eighteen years of secret practice. “The Article on Marriage” became obsolete and was later removed.
From this site : http://www.ils.unc.edu/~unsworth/Mormon ... wives.html
Mosiah Hancock's biography seems to be evidence of a marriage between Fanny and Joseph...
“Therefore Brother Joseph said ‘Brother Levi I want to make a bargain with you – If you will get Fanny Alger for me for a wife you may have Clarissa Reed. I love Fanny.’ ‘I will’ Said Father. ‘Go brother Levi and the Lord will prosper you’ Said Joseph – Father goes to the Father Samuel Alger – Father’s Brother in Law and [said] ‘Samuel the Prophet Joseph loves your Daughter Fanny and wishes her for a wife what say you’ – Uncle Sam Says – ‘Go and talk to the Old woman about it twill be as She says’ Father goes to his Sister and said ‘Clarrissy, Brother Joseph the Prophet of the most high God loves Fanny and wishes her for a wife what say you’ Said She ‘go and talk to Fanny it will be all right with me’ – Father goes to Fanny and said ‘Fanny Brother Joseph the Prophet loves you and wishes you for a wife will you be his wife?’ ‘I will Levi’ Said She – Father takes Fanny to Joseph and said ‘Brother Joseph I have been successful in my mission’ – Father gave her to Joseph repeating the Ceremony as Joseph repeated to him.”
- Mosiah Hancock Autobiography, pp. 62-63