"Joe" was Joseph P. Ready. We believe Joe was born in the mid-1800s (his wife, Amelia, was born in 1845). The children would have been born before 6 Apr 1881 (William's birthday). I haven't found any records yet, but family history, told by different brothers and sisters, have different ages for each child. So my best guess is that John was born in the late 1860s or early 1870s, Maime would have been born in the middle-to-late 1870s (maybe 1874 or 1878).
When Amelia took William to her father, Benjamin Trenholm, she placed Maime in a convent and/or orphanage. The guess is that John stayed with his father in Boston.