Three sisters, Anna Duffy, Nellie Duffy and Katherine O’Connell, were grantees as joint tenants of a conveyance of real property. Nellie conveyed her interest in the property by deed to Anna. Anna Duffy died leaving a will that bequeathed her interest in the property in equal shares to four nieces (plaintiffs). The nieces brought suit against Katherine O’Connell (defendant), the last surviving sister, to partition the property. The nieces argued that Nellie Duffy’s deed severed the original joint tenancy entirely, leaving O’Connell with only a one-third interest as a tenant in common. Under the nieces’ theory, Anna Duffy would be the owner of an undivided two-thirds interest in the property as a tenant in common at the time of her death. O’Connell argued that Nellie Duffy’s deed only severed the joint tenancy the sisters shared with respect to Nellie’s one-third interest, thereby making Anna Duffy the owner of a one-third interest as a tenant in common and the owner of an additional undivided two-thirds interest in joint tenancy during her lifetime. At Anna’s death, O’Connell argued, the two-thirds interest vested entirely in O’Connell, leaving only Anna’s one-third tenant in common interest to pass as an asset of her estate. The probate court agreed with O’Connell and held that each of the four nieces thereby inherited a one-twelfth interest in the property. The nieces appealed and the court of appeals affirmed the probate decree. The nieces petitioned the supreme court for review.