If you look at the census you will see how they got the name Mahulda, though there is no one by any name close to that in this family.
Malinda Ann Alford is listed in the 1870 census abt. line 32 as M.A. Alford, age 9, female, white, born in AL.In the 1880 Census she is listed as what reads as Mahulda is some sources, age 19, white, female.
Isabelle Alford is listed in the 1870 census as Isabelle Alford, age 5, female, white, born in AL.In the 1880 census she is listed as Isabela, age 15, one source I saw (the Mormons I think) listed it as something else, but the ages match, as well as the family and the writing is definately unclear on this page.