Hi Teri , Did a bit of research on the Isle of Man , there is no Susan Davis on the 1841 census , however there are a family of McNeilly's there , including a John aged 54 ,with wife and children , but no younger John's . On the IGI website there are listing's for your Susan Davis , John McNeely and John McNeilly , however they have been posted by members , which could be some of your relations and are estimates only , HOWEVER , there is one posting that has come from church records !!!!
Susan Davis , father George Davis , mother Jan born 7/9/1839 , christened 29/9/1839 Cloghran-Swords , Dublin , Ireland .