Mysterious Quinn Children

Whilst researching the Quinn family, I came across the 1860 census for Cherry township where Elizabeth Farrell Quinn is living with John Farrell and Mary Farrell. Whether or not these two were married, I do not know yet. However, I find it interesting that Elizabeth is enumerated as Farrell though she is most definitely a Quinn. All of her children are enumerated in the household as well. There are also two children, Eliza, age 7, and William, age 2, both born in Ireland, also enumerated in the home. Who are these mysterious Quinn children? Are they Elizabeth's grandchildren? I cannot find them on the 1870 census, and they are obviously too young to be on the 1850 census. Are they even Quinns? It is not uncommon for mistakes to be made by the enumerator. Obviously Elizabeth was enumerated with her maiden name. It seems more than likely that John Farrell is her brother. So that presses the question... are the children really Quinns or are they Farrells?