This is kind of late but I just saw you message today. I have just recently gotten on the internet.
I found your Joseph Allen in the 1850 Ill. Census. It is on Roll 124 Page 239.
It lists the following:
Joseph Allen 54 born in NY Cinthia a44 born in NY Julins"23 born in Ill. Laborer Calvin"11" Pamelia "11" John"9" Diansa"7" David"5" Thomas"3"
It does not show Mary Jane living with them at this time.
Hope this is some help.
I am looking for a Cyntha Allen who Married William Stanfield.I do not have any information about her except that William and his Father Samuel Stanfield were living in the Scott County Illinois area in the early 1830's and they had a close neighbor whose name was Thomas Allen. Also William named one of his sons(My Great Grandfather) Thomas Allen Stanfield. Thomas Allen Stanfield was born in 1834 in Alton Illinois just south of Springfield Illinois.